Integral Calculus
written by:
mcerotic

Hi there, Lindsey back again. Lots of you seemed to enjoy my story "Differential Calculus" so I'll tell you what happens next if you like. Let me start by bringing you up to date on who I am and how I got here. I'm a student majoring in elementary education in North Carolina. I'm 5' 7" and I've got dark brown hair and 38D breasts (yes, they're big). In fact if you want to know what I look like there's a photo over on my other author profile at just_plain_innocent (and don't forget to read those stories while you are over there).

I was failing a math class last semester so I tried to make a sex for a grade deal with Paul the professor for the course. But he had other ideas: he would punish me if I didn't learn the material. My bottom may be sore but I learnt! He also put a padlock through my inner lips so I couldn't have sex with anyone else without his permission. Only he has my cunt-key. You'd think it'd be a real turn-off not to have full control of my own body, but actually it is surprisingly erotic being so submissive.

Of course I'm not completely at Paul's mercy. I can still masturbate for instance. In fact earlier today I was sitting at my desk reading some erotic stories on the internet. I was meant to be working on an essay on Piaget (yawn) but procrastination got the better of me. As I started to get aroused I took off my jeans and started to touch myself through my panties. I don't always come, sometimes I like to read stories and just keep myself aroused for ages. But this time I was seriously aroused so I slipped off my panties too. My shaved lips feel really soft. I used to use a vibrator at this point, but I can't use the cock shaped ones (because my cunt is locked, remember) and I don't like to use one of those little clitty ones since it buzzes annoyingly when it touches the padlock. So I just used my fingers on my clit the good old fashioned way that I discovered when I was a girl. I like to make small circles around it, not quite touching it directly, as my excitement builds and then when I finally decide to come I expose my clit more directly. It only takes a few shorter faster strokes to take me over the top into nirvana.

Anyway, enough of telling you how I masturbate. I'm in my room finally starting that Piaget essay on the stages of children's development. Of course I've put my jeans back on again by now. There's a knock on my door. It is my ex-boyfriend. You remember I dumped him because I was too embarrassed to tell him about the padlock. That's not a very good reason, is it? Well, he's being really nice to me and this time doesn't seem to be trying to get into my pants again. So, being a perverse female, I immediately want him in my pants and soon we are on my bed cuddling and kissing and he unbuttons my shirt and has my bra off and he's playing with my breasts. Remember they're big. So I'm there topless, feeling his cock hard in his jeans, feeling his tongue as he caresses my nipples. I'm wondering how I'm going to break it to him that I'm all locked up. I decide to tell him an edited version.

"Do you know what happened to me at the end of last semester?" I start. He's a bit grumpy about talking since he just wants to get my jeans off. "I had to get an A on my math class so I made a deal with the professor which was that I'd focus so hard on my calculus that I would forgo vaginal sex for a few weeks. He took the deal and I got my A grade." By now my boyfriend's intrigued. I mean, wouldn't you be in his place. "And don't think you are going to fuck me up my ass," I tell him. I know he's a bit freaked out by anal sex because he's never done it before, but also I know that if you want a man to do something the best is to make it unattainable, make him think he is getting it against your will. He wants to know what's to stop him just slipping his cock into my pussy. I can't look him in the eye as I tell him. "My pussy is padlocked shut." Of course he immediately wants to see so I stand up, slip everything off so I'm naked and lie back down with my legs spread showing him the small brass padlock threaded through my inner lips, labia minora I think they're called technically, although that sounds more like a character from Greek mythology. My spellchecker reckons it should be labia menorah, which must be the Jewish version. He examines the lock which sends some tremors of pleasure through me. "Lick me," I beg him and I roll over onto my front. I've got a pretty good ass, even if I do say so myself. I reach back and spread my ass cheeks and he takes the hint. I love getting my asshole licked, not that it has happened very often. He's getting into this which is good. He hasn't even asked about the key yet. So his tongue is on my asshole and I feel myself relaxing and soon his tongue tip is starting to penetrate into me. It feels so good, there are zillions of nerves there apparently, but it also feels dirty and taboo which makes it more exciting. I tell him that there is lube in the drawer by my bed and he squirts some between my cheeks. Probe it is called, a sort of thick gel. Pretty appropriate I'd say. He rubs my asshole with it and soon he is fucking me with one finger.

I'd better get him hard enough so I unzip his jeans. Actually he's pretty hard already after playing with my ass. I put some Probe on his cock and stroke him as I get him undressed with my other hand. Soon we are both naked. I take him into my mouth. This Probe stuff may be good in an ass but it doesn't taste that great. But his cock is rock hard, I think he could penetrate sheetrock, never mind my tight rear entrance. I let him move over my back as if he is in command of the situation and I make some token resistance pushing his cock away from being anywhere near my butthole. But soon I reach back and guide his cock so that he is resting in the dimple between my cheeks. Locked and loaded, as it were. He pushes forward. I love this feeling, it is so intense and it requires a lot of trust to get his cock into me without the pain becoming too much. I lie on my hand so that I can stroke my clit as his cock slips into me for the first time. The first time for him, that is. I've had Paul's cock up my ass a few times now. It is starting to feel really good as my asshole gets used to the invasion. He starts to fuck me, thrusting in and out. He's really getting into it. My finger on my clit could make me come any moment, but I'm holding off until he is ready. I've heard him come so many times before I know just when he is close. When I hear his breathing getting heavier I stroke my clit a bit harder and let my orgasm arrive. I can feel my asshole milking his cock, which is too much for him and then I can feel his hips thrusting like a rutting stag as he empties his come deep in my ass. He collapses onto my back. I can feel his cock going soft in me. I gently squeeze him out. I don't think I'll have too much difficulty persuading him to fuck my ass again in the future.

We've both got schoolwork to get done so he doesn't stay that much longer. Soon he is dressed and kissing me goodbye. I'm back at my desk working on Piaget again. I bet you don't know what the ‘concrete operational stage of development' is. And it's not when you move to suburbia and build a patio. There is a pleasant throb in my ass and I'm feeling in a really good mood. Talking of stages of development, of our relationship this time, I guess my boyfriend and I are back together again. Or maybe that was just ex-sex. Who knows?

**

I'm having a weird day today. Everyone around the campus is looking at me a bit strangely. I keep checking to make sure my shirt hasn't come unbuttoned or something. Eventually I bump into one of my girlfriends and the first thing that she asks me is whether it's true. "Is what true?" I say. "You know," she says, blushing slightly. It turns out that my boyfriend (well, I don't think he's my boyfriend any more, but I'll deal with that later) has told his friends about the padlock and they've told all their friends and so on. To make it worse, since he doesn't know about the key, he thinks I'm about to present it to him as a token of my love or something. "I think it's really sweet showing your commitment by giving him a key to your pussy," my girlfriend says. As if.

My cell-phone rings. It is the local piercing parlor just off the campus. It's run by a couple of somewhat intimidating Goths but I've heard they are pretty good piercers. I've never been there, I did my own piercings. It didn't hurt that much and the price was right. Anyhow, this place wants to pay me for a photograph of the padlock. Apparently they've had a stream of female students coming in wanting a padlock like mine in their pussy but nobody's sure exactly what it is like. They want to give the key to their boyfriends as a symbol (but I bet they keep a duplicate, I certainly would). The Goths offer me a hundred dollars, and I say two hundred hoping to get an extra ten or twenty. They say ok immediately. Shit, I should have asked for five hundred.

I have an hour before my next lecture so I wander over there. I could do with the money, I have to admit. They take me into the back where they normally do the piercings. It seems they have this one room they use for all female genital piercings that has stirrups like in a gynecologist's. I slip off my jeans, take off my panties and put my feet in the stirrups. This feels really weird. Somehow in the sterile environment of a doctor's surgery it is ok, but this feels more like stripping in a biker bar. At least it is the female Goth that takes the photos, although who knows, she's probably a lesbian getting off on it too. But first she wants me to sign a model release form for the photographs. You'd laugh if you saw me, lying there with my legs spread doing paperwork. So she takes about a dozen pictures of my pussy and the padlock, moving the lamp each time. But she decides she wants before-and-after photographs. Well, of course she can't really do that, I've already got the padlock. What she means is that she wants a picture of my pussy without the padlock. She asks me to unlock it and I have to admit I don't have the key. "Can you call your boyfriend?" she asks and I am too slow to think up a good cover story and I admit that even my boyfriend doesn't have the key. This kind of freaks her out, the idea that I have locked up my pussy and thrown away the key. "I can always saw it off," I joke. Talk about the amount of trust that would take, to let someone a few fractions of an inch from your pussy with a hacksaw. "Doesn't someone have a key?" she asks and I tell her that I'm a slave and only my master decides when and where I have sex. Surprisingly, this calms her down. I guess she has pierced slaves before and she knows that a slave would never ask her master to unlock her for something so trivial.

So now I've got a couple of hundred bucks in my pocket for ten minutes work. I guess I should go into porno, don't they get several thousand dollars for a day's work? But I don't think I could do that. Flashing my pussy for a photo is one thing, fucking a stranger is something I'm not about to start doing. I've had enough bad experiences earlier in my life to only want to fuck nice guys who don't have too many problems. Or nice women, come to that.

**

Today is even odder than yesterday. There are lots of pictures of my pussy with the padlock on all the notice boards on those pillars around the campus and in the hallways of the buildings, with those little tear off strips thingies at the bottom with the piercing parlor's number. I only really know it is me since the Goth lesbian (I know, she might not be) showed me the photographs before I left yesterday. It's not like I'd be able to pick out my own pussy from a lineup, especially now that half the women on campus seem to be getting padlocks pierced into their pussies. I have to admit, when I signed the model release I wasn't expecting meet my pussy whichever way I looked. Normally it takes some effort. Not to mention a mirror, hehe. Anyhow, I'm somewhat self-conscious because everyone knows it is me in the photograph, you would be too.

I'm meeting another of my girlfriends, Ashleigh, for a coffee. We have this break when we don't have anything to do but we don't have time to go back to our rooms so we have a regular latte date. A lattay dattay we call it. She's already in line when I walk into the café. We get our coffees she walks past lots of empty tables to sit down in the corner far away from everyone. She asks if it is true about the lock. By now, of course, there are so many rumors that half of them are way off-base so I have to make her explain before I can even answer. What she wants to know is whether it is true that my boyfriend doesn't have the key. She's a pretty close friend so I trust her (that will turn out to be a mistake) and admit that my math prof has the only key and I got an A grade. I don't tell her than I actually learned enough to make my grade genuinely, given the incentive of my painful punishments after every test Paul gave me. So she thinks that I let my prof lock up my pussy for an A grade. I can't claim to be completely innocent here, after all I did plan on fucking him for an A grade, and locking up my pussy is perhaps less far along the scale, even if it is kinkier.

Ashleigh tells me that she has a little kink of her own. Not as extreme as mine, she admits. But conspiratorially she tells me she never wears any underwear, no bra, no panties. I look her up and down. She's wearing a shirt, not too thin but not exactly thick. Now that I look closely I can see the points of her nipples where her shirt pulls against her breasts. She can get away with it because she has small breasts. She's wearing a short skirt, which more daring than I would be without underwear. Of course I can't see up it at all, but if it'd been me I'd have felt really exposed, as if everyone could see everything even so. Not that there would be much point, in my case. You can just look on the campus notice boards and see everything I have hidden up there!

"I bet you won't dare wear a skirt with no panties," she says. Of course, you know me. Well, you don't really, but by now you've probably realized that a dare like that is red rag to a bull (apparently they are actually color-blind but I'm not going to check on it right now). I'm wearing a skirt today, not as short as hers, but nonetheless a real not-jeans feminine skirt. I get up and go to the restroom, slip off my thong and put it in my purse. When I stand up after peeing I can feel the padlock swaying, tugging on my lips reminding me of its presence. I decide to leave my bra on. She has little conical tits and doesn't really need one. When I go without a bra the ocean billows under my shirt like on a surfing beach and nobody can keep their eyes off my chest. I feel really vulnerable as I walk back across the café. I sit back down with her. "No panties," I say. "Really," Ashleigh says as she accidentally-on-purpose knocks her coffee spoon on the floor. "Show me," she says as she bends down to pick it up. I can't really get out of this, can I? So as she scrabbles under the table for her spoon, I casually lean back and raise my arms in the air and open my legs as if I'm sleepy and stretching. She pops up so fast she bangs her head on the table. "It looks beautiful," she says. "My pussy?" I ask puzzled. "Well, the gold padlock in your pussy," she says. "It's only brass," I have to admit but I'm feeling pretty sexy with no underwear and a straight friend staring up my skirt checking me out.

We split up and I go to my next lecture. But there is a sign on the door saying the prof is sick and it is canceled. Postponed, more like, we all agree. When did a prof being sick mean we didn't have to learn the material anyway? I walk back towards the cafeteria. I bump into a guy I know casually and we sit on a bench by one of the trees in the courtyard there. Luckily he either doesn't know or is too polite to mention the padlock. He must be the first person like that all day. A gust of wind blows and my skirt flies up to my thighs. I push it down immediately but not before he cops a good look at my pantiless (not to mention shaved) crotch. I can tell by the way his eyes pop out of his head that he's noticed. Shit. Not only am I going to have a reputation for my padlock but everyone is going to assume I walk around everyday with no panties and with the padlock swinging between my thighs. I'm just leaving when I bump into Ashleigh again who is at a loose end for an hour.

So Ashleigh and I go back to my room. Once we are in the door she wants to watch TV. It's the middle of the morning so there's not much on, just some soaps where we have no idea what is happening since we are normally in class. The acting is really bad but we pretend to be interested so that we sit down on the sofa together. Out of the blue she tells me I'm beautiful. I'm a bit surprised but I tell her she is really beautiful too. What else can I do? It's not a lie either. She is the daughter of an Indian father and a white mother with lovely light coffee colored skin, and a great figure. I've already told you she has pert breasts. Of course she has long black hair. I think about the fact that she's not wearing any panties and I guess she has a triangle of silky black pubic hair. I'm really surprised when she asks me whether I've thought about doing something with a woman. I've fooled around with women before but only kissing and cuddling. So I tell her that women can be really gentle kissers, and that I like a little aggression but with passion. That's like an invitation to her, so she leans over and kisses me. Aggression and passion, just what I asked for I guess. Of course I kiss her back. Well, I'm only a horny teenager after all. Her hand is already inside my shirt stroking my breasts. I feel her hand on my knee, moving up taking the hem of my skirt with it, stroking up the soft skin on the inside of my thigh and homing in on my pantiless pussy. Wow, I'm so wet by the time she touches me there. I put my hand on her knee. She spreads her legs in invitation so I move my hand up toward her pussy. I've never touched another woman's pussy before. Her lips feel so soft, different from mine in some way. She seems even wetter than I do. I touch her like I touch myself when I masturbate, sticking a finger inside her to get some juice to stroke her inner lips and to rub on her clit. It takes no time before we are both naked. Her breasts really are perky with hard little dark brown nipples and so, of course, I want them in my mouth just like my breasts are already in hers. I was right about the thick black pubes. She is pushing me back on the sofa and sucking my padlock. I think she needs to get one of her own but I'm loving every moment of it, especially once she loses interest in my lock and starts to pay attention to my clit which feels like it is sticking out about an inch, begging for attention. She straddles my face and those pretty brown lips are just a short distance from my tongue so naturally I lick her out. I'm not very good at this because I've never done it before. Her tongue is in my pussy now, which is only fair because I've got mine in hers. She tastes slightly like curry. Is it really possible that your pussy juice tastes of what you eat? I wonder how I taste. Hamburger and fries and Caesar salad? Women kiss so tenderly and when they lick you out they really know what they are doing. I guess if you own a clit you are better placed to know just how it likes to be handled. Or tongued, hehe.

Although it's fun being licked by a woman it's just not the same as a guy. It lacks the anticipation of the hard cock that will soon penetrate me, the roughness to come. I let her make me come. I have to admit she's pretty good at it. I'm sure she must have done it many times before. I'm obviously not doing too badly myself since she is enthusiastically thrusting her pussy into my mouth as I tongue her clit, close to coming. I stick a finger into her pussy and massage her g-spot as I work her clit toward the final fence. "Don't stop, don't stop," she urges me (not that there was any chance of that). "Don't stop, don't stop," she keeps saying as she comes, and I tongue her clit prolonging her climax as long as I can. We sit up, slightly embarrassed now that we are not so sexually charged. "Are you ok," she asks. I tell her I'm fine, it was not my first time with a woman although it was my first time with an Asian. Well, semi-Asian. She says that the moment she saw my padlocked pussy under the table in the café that she wanted to taste it. This padlock thing seems to enable as much sex as it restricts.

Ashleigh leaves. I find out later that she bumps into my boyfriend. Unfortunately she doesn't know two things. One, that he is no longer my boyfriend for being such a creep as to spread the fact that I am padlocked around the campus. And second that he doesn't know that only my math professor has a key. He still thinks he is getting it as a gift. So it's not good when she repeats to him what I told her earlier in confidence. I can't really blame her, she naturally assumed that my boyfriend already knew everything she did.

So now that it is late afternoon I seem to be even more the center of attention again. I'm getting used to this and try to ignore it, and resist the temptation to ask someone what everyone is saying about me this time. But eventually I meet another friend, who asks me whether it is true. I assume he means about the padlock, since everyone seems to have heard about it. But then I realize that maybe there is now a story that I never wear panties. "Is what true?" I ask. That my math prof has the only key? Well, that's a surprise. How has that got out? I can't really deny it either, so I mumble something unconvincing and rush back home.

**

Let's recap. Everyone on campus (well, probably not everyone but anyone who counts) knows that I have a padlock through my pussy lips (they even know exactly what my pussy looks like, although I'm a woman so they all seem pretty much the same to me). They know that I never wear panties. It's not true but then again it's not the sort of thing that you feel like proving to every guy you meet. And they know that my boyfriend (ex-boyfriend, the rat) doesn't have a key and only my math prof does. Oh yes, and I got an A last semester after doing horribly at the mid-terms. Naturally they assume that I got let me professor lock up my pussy for an A. Either everyone thinks I'm a slut or they think I'm the most out-there girl at the college, I'm just not sure which.

On top of all that embarrassing reputation, today is the first day of my "Integral Calculus" course with my master as professor.

I arrive in the lecture hall a few minutes early. I like to get a seat at the front. After all he is my master and I'm his slave. For my last class there were about twenty people, roughly half men half women. When I walk into the theater it is packed, and largely with women. They are mostly sitting high up on the raked seats so the front row is still empty and I can sit in my usual seat. I get there. Still a few minutes to go. There is a clock at the back of the room, to keep the professor on time as much as anything. I turn around to look how long before the lecture will start and I'm amazed. I can see the glint of the bright auditorium lights reflecting off brass everywhere I look. I don't need to see the details lurking in the darkness of their skirts, I know they all have padlocks. And they are not sitting with their legs crossed. What have I started?

Professor Paul enters. I've not seen him for a couple of weeks so my pussy, no my cunt since it is Paul, spasms with excitement. He starts his lecture about how integration is the opposite of differentiation. How it can be used to work out things like where a plane is merely by measuring all the accelerations with gyroscopes. I have to think everyone is rather less aroused now that the subject really is math. Every time he asks a question, one of the nerdy guys shouts out the answer. I'm not trying to pretend that I know the answer either, but I don't think any woman spoke for the whole hour. I don't know how Paul could handle it, all those blatantly pantiless pussies with their brass fireflies drawing maximum attention up between their thighs. And not just any thighs, these are the pussies of many of the most attractive women on campus that are on offer.

Finally the period is over. "Before you go," says Paul, "I noticed that there was no class participation by any of you women. Consequently I've decided to add a women-only lecture at 7pm this evening to go over the same material without all the male mathematicians answering every question."

I know Paul better than anyone else and I realize that he must have something interesting in mind. That is to say, very sexual. I know from my own experience that he will never pass anyone in a course if they don't know the material, but that he is quite happy to use every lever to get a girl to learn.

The guys look clueless when Paul continues. "I expect all keys on the lectern by the time I arrive at seven." The women all know exactly what they must do.

Wow. He will only give extra tuition to women if they give up their cunt-keys like I did. He will have a couple of dozen slaves. I'm hoping I'll still be special, primus inter pares, the first among equals.

**

You don't need me to tell you that tonight I'm in the lecture hall. Each woman who arrives has more or less the same procedure. She'll come in and sit down causally. And then, when she thinks nobody is looking she'll saunter to the front of the room and casually drop her key onto the pile. Of course we all watch every movement. I don't think there is an unpadlocked woman in the room. However, I can't put my key there since I don't have it so I feel even more self-conscious. Do the other women think I'm not padlocked? Or do they already know that I don't have my own key?

Paul has arrived and is talking now. He is explaining how things work. Of course I could make a pretty good guess at what he is going to say since I've lived it for weeks, but the other women seem surprised. Just like I did, they assumed that granting access to their pussies would automatically translate into an A grade. Paul is reducing everything to a few rules.

"Rule 1: Everybody has to be completely obedient. If you are not prepared to submit to my every command then I can't teach you and you must leave.

"Rule 2: You can only have sex when I say so. Actually I'm not quite that strict, I just require your cunts to be locked and for me to have the key. You can use your imagination as to how you can get pleasure while the lock is in place." I feel a slight throbbing in my ass from my boyfriend's (bastard) cock yesterday.

"Rule 3: you will actually learn Integral Calculus. This is not a sex for a grade deal. This is an innovative learning process. As teenagers your hormones are on fire so the best way to incentivise you to learn is to use that fact. Each week you will learn your chapter, I will give you whatever advice you need to understand the material completely, and I will punish you if you don't.

"Rule 4: If you break any of the other rules you will also be punished.

"Right," Paul continues, "Anyone who doesn't agree to the rules should leave."

I'm surprised nobody gets up. If I'd known how painful the canings and clamping and spanking would be I'd probably have left. But I needed an A grade. Most of these women probably just think that this is an easy way of having a good grade on a hard course that will look good on their transcript. Beautiful women are too used to having everything their own way. I mean they never even get speeding tickets since they just flutter they eyes at the cops and stick out their boobs. Even I've got away with that sort of thing before.

"OK, starting with the front row I want each woman to come up here." Paul gestures to a young blonde girl on his right and she sheepishly creeps forward, embarrassed to be the first .She's attractive enough to be a model so it must be odd for her to feel out of control with a man. Maybe even a first for her since puberty. When she gets to the front he asks her to find her key. Well that is harder than it sounds since the locks are largely the same and so the pile of keys are mostly of one type. "It's number 51," she says as she searches. Soon she finds it and passes it to Paul. He makes her sit down on a chair and spread her legs. She is red-faced and clearly very embarrassed, and can only force herself to part her thighs reluctantly, facing away from the class so that only Paul can see her pussy. He seems to ignore the fact that one of the most beautiful women on campus is showing him her most intimate folds. He simply reaches down, unlocks her padlock and removes it from her lips. Then takes a new one from his pocket, holds her lips gently and threads it through the pierced holes in before clicking it closed. He hands her back the original lock and the key. Only Paul has her cunt-key. Paul has guessed that every woman in the room already has a spare key, and perhaps even their boyfriends have unfettered access to their pussies. Now that everyone realizes what is going on, and that Paul cannot be so easily tricked, a few women leave the room, pushing on the crash-bars on the doors as quietly as they can. Paul continues with each woman, white, black, hispanic, asian. Even I have to have my lock changed, whether for show or because it has the wrong key I'm not sure. I feel proud to continue to be Paul's slave and submit my cunt to his control. But my new lock is lighter than the old one, the steam-engine of padlocks, and I miss the heavier feel of it when I walk.

As each womans's pussy is offered to him in turn, Paul removes the existing lock from her pussy lips, whether they be pink, crimson, mahogany or brown. He then pulls their lips out tight to open up the two piercings and threads in another padlock from his pocket. Presumably they all have the same master key, the cunt-key to end all cunt-keys. How much would the lotharios of the campus give for that baby?

Finally Paul has swapped every woman's padlock for one to which only he has the cunt-key. "Tonight's lecture is over, be here at 7pm the day after tomorrow." And Paul walks out of the back door leaving a room of beautiful women all of whose pussies he owns.

**

Tonight is my night to go to Paul's for my personal tuition, but something interesting happened earlier today that I have to tell you about. This friend of mine, Glenn, from home drove over to see me. It's a couple of hours drive so it's pretty sweet of him. He's not that kind of friend. I mean I've never fucked him, never even kissed him. He's cute, but somehow the magic was never there and we never made out. So he's in my room and he's being really sweet to me and he's the only guy around that I can be pretty sure doesn't know about the padlock since he isn't at my school. He's sitting on my bed and we've split a bottle of wine and I'm feeling pretty affectionate. I'm behind him and I wrap my arms around him. I'm just being friendly but pressing my breasts against his back feels really good, I have to admit. I kiss his neck and nibble on him slightly. He smells good. I know I'm turning him on and I shouldn't, after all I already have a boyfriend. Well, I suppose I don't since he's been such an asshole but I've not actually dumped him yet. So he turns his head and we are kissing. He's so nice that he even asks permission before he puts his hands on my breasts. Like I'm going to say no, right? Anyway, Glenn gets all my clothes off, not like I'm resisting or anything. I get him almost naked, he's just wearing a T-shirt. His hand and mouth are all over my tits and sucking my nipples. I move over him and rub his cock head up and down my slit which is really wet (duh!). Of course I can't fuck him because of the padlock and I'm too shy to ask him to fuck my ass. It's not exactly a first date kind of thing, is it? At this point he probably just thinks the padlock is just a couple of thick ring piercings if he's noticed it at all. I've been careful not to let him get too good a view between my legs yet. Finally he pushes me back onto my bed and starts to lick me out. "Wait," I say, "I've to something to tell you," And to my surprise I burst into tears. I tell him the whole story, going to see my professor to get my grade up, the lessons, the punishment, willingly replacing the padlock at the end of the semester, everyone finding out, the piercing parlor, the ads around campus, the trend I've started amongst the campus hotties. Everything really. Well, apart from the anal sex, I don't know if that would turn him on or off yet, and besides it is my pussy that is aching for his cock right now. And that has a fucking padlock in it. Or a not-fucking padlock to be more accurate.

So Glenn licks me out and makes me climax a couple of times, and I suck him off and swallow his come and all that. But it's just not enough, I need the penetration thing. He agrees to accompany me to my ‘extra' math class that evening at Paul's house. So here we are walking up the driveway to Paul's front door holding hands like a couple of middle-schoolers. I've no idea what Paul's attitude is going to be to my bringing another guy along. He acts as if nothing is different from usual when he opens his front door. We go into his living room, he gives us a glass of wine each. He tells Glenn that he can watch whatever he wants while I have my class: a DVD, regular TV, cable. Even a porn movie. That would take brass balls to sit and watch a porno on his own while I study integral calculus across the room. So we go over the first couple of chapters in the textbook while Glenn watches some PBS documentary about South America. I'm sure that's not what he'd choose if he were at home, Wheel of Fortune is more his style, but I don't say anything. He's a really nice guy and I know he's not entirely comfortable in a college environment anyway. Plus, don't forget, I still want his cock in me even though I'm sitting here learning that integration is the opposite of differentiation and you always end up with this extra constant (because that would differentiate to zero so wouldn't count, I'll bet you didn't know that). Well, we get to the test at the end of the hour and I tell Paul that I've got a favor to ask him. He already seems to know what it is since he reaches in to his pocket and gives me my cunt-key. Maybe it's even the master key to the campus but I doubt it. So I'm free to leave and fuck Glenn but somehow I don't want anything that simple any more.

I go over to Glenn where he is watching this crap about sloths in the Brazilian jungle. Which reminds me, I'd like a Brazilian instead of having to shave every day or two, but I can't afford it. I can see there's a pile of porn DVDs there so I just take one at random. "Student First Timers #17". First time on a porn movie I presume, you'd have a hard (hehe) time finding many student virgins. In real life, even Charlotte Simmons would have got laid during high school in her hillbilly town. I put the movie into the DVD and turn it on. The three-toed sloths are replaced with two female students, one white and one Indian in a sixty-nine. It reminds me of me and Ashleigh yesterday. Glenn is torn between watching the TV and wondering what I'm going to do next. The white girl on the TV is doing delicately licking the Indian's pretty brown pussy, and she's moaning with excitement as I gyrate in front of Glenn and slowly work my jeans down over my hips. I'm wearing a thong today. I used to love to wear jeans with no underwear but it is not so comfortable once your cunt is padlocked. I turn around and slip my thong over my ass. I know without looking that both Paul and Glenn's eyes have moved from the students on the TV and now are glued to my pussy as it comes into view, with the little brass padlock dangling between my thighs. I turn around to face Glenn who isn't at all sure how to react. I reach down, unlock the padlock with the key and remove it. "My cunt is open," I say. You don't need me to tell you I'm pretty turned-on at this point. I pull my T-shirt over my head, unclip my bra and release my breasts. I am feeling so exhibitionistic as I tweak my nipples to make them hard. I can feel my juices running. It is so much more obvious when you are shaved. It feels like they are running down my thighs, I'm so fever-pitch aroused.

I've always wanted to have a threesome with two guys giving non-stop attention all over my body. I've had a threesome where I was one girl of the two but never one where I was the center of attention. Now is my chance. I grab Glenn's hand and pull him to his feet and then I direct him in the direction of the bedroom. Just in case he wasn't planning on joining in anyway, I beckon to Paul as I leave the room. Soon the three of us are in Paul's bedroom. I push Glenn back onto the bed and slowly undress him, licking each area as it becomes uncovered. His legs, his arms, his nipples, his navel and finally his lovely big hard cock. I start to suck him. This is a pretty sexy scene, right. I mean Glenn is pretty well-built and he is naked on his back on the bed. I look pretty good too (hey, it's not just my opinion) and I'm naked straddling his legs with his cock in my mouth and my breasts brushing against his thighs. My math professor stroke master (stroke-master hehe) is standing watching us, with a perfect view of my juiced cunt. I know without looking that he is hard as a ramrod.

I move up the bed and kiss Glenn. "It's OK," I whisper. I know he's nervous as hell. Don't forget we've never fucked before. I can feel his cock against my belly. I move a little bit further up and start to stroke my clit up and down his cock, lubing him up with my juices. I sit up and kind of fuck him with my wet lips wrapped around his cock. Paul comes over and his mouth is on a nipple. He lost his clothes somewhere along the way so I grab his hard cock and start to stroke him as I slide Glenn's cock back and forth in my cleft. I only need to move my hips slightly and on the next stroke Glenn's cock slides into my hot pussy. His cock is big and I have to work him into my tightness. Paul's hand is on my ass stroking my cheek. No, he's working a finger into my ass with my juice. Glenn reaches up and squeezes my breasts. Two men all over my body is as good as I imagined (yeah, it's one of the things I think about when I masturbate). Paul moves behind me. I can feel his cock against the crack of my ass as I fuck Glenn underneath me. Paul's cock seems to be all lubed up, I don't know if it is my juice or if he found some stuff somewhere. I feel Paul's cock at my asshole, knocking on my door for entry, as it were. I'm about to try something new I've only ever seen in porn movies. I push back against Paul and gradually work his cock into my ass as I thrust my hips to fuck Glenn. Two men inside me, I feel like I'm one hundred percent sex. Glenn has my breasts and Paul has my ass. He starts to smack me, playfully rather than painfully, but pretty hard anyway. It's all it takes to make me come but I know I'm going to have a couple more orgasms before I let the men have theirs. After all, it's all over after that, at least for a bit.

Time for a change in position, fucking two men is tiring! I leave Glenn underneath but squat over him facing away from him so that he gets a great view as I lower my body and his cock vanishes into my ass. I wonder if he's an anal virgin. Not exactly the moment to ask, is it? It feels good as I thrust my hips back and forth impaling my ass on his cock. I lean back against Glenn's chest. He reaches around and holds my breasts tight, which feels really good. Paul doesn't need any guidance and moves between my legs and slides his cock between my lips into my welcoming cunt. Wow, what a feeling? Have you ever tried it? Well, that assumes you are a woman of course. It's hard to really thrust in this position, I have to let the men do all the work.

Paul pulls out of me and I take the opportunity to lie on my back in the position apparently approved by missionaries. I doubt they would approve of this though. As Glenn moves over my body and enters me, Paul slips his cock into my mouth. Mmm, a girl could get addicted to this. I'm close to coming and I reach down and touch myself for like three seconds and then I'm exploding with waves of pleasure. I have to concentrate to stop myself biting Paul's cock, it's that intense. I think I'll let them come now. Paul first, I've got more control of my tongue than my pussy. I start to fuck him with my mouth, taking him into the back of my throat. He can't take it for long like this and soon I feel his cock buck on my tongue as he empties himself into my mouth. Next I squeeze my pussy muscles. It feels good to me but I know that it feels even better for whoever's cock is in me. I'm thrusting my hips as hard as I can underneath Glenn, I like it hard. It doesn't take long before Glenn moans with pleasure as his climax takes over his body.

I lie there on the bed. The two men are kissing me all over, little butterfly kisses on the inside of my thighs, my breasts, my stomach. I can feel my pussy waking up again already as their kisses get closer. I turn onto my side and lift up my upper leg. Paul is behind me working his way down the crack of my ass. Glenn is working his way towards my slit across my belly. Paul's arrives at my puckered rosebud and Glenn just enters the head of the valley between my outer lips. This is so exciting, I'm about to have two tongues in my cunt. I can't really stop my hips from making small thrusting movements, alternately pushing the root of my clit against Glenn and my asshole against Paul. The two of them move further between my legs. Paul's tongue is in my cunt now, like a small cock fucking me, and Glenn has arrived at my stiff clit. This is the most fantastic feeling, and since the two guys just came I don't feel the least bit guilty at not giving their cocks any attention yet. I won't be able to take this for long without coming. I feel a hand on my breasts, I'm not even sure whose since I've got my eyes shut just reveling in the strong feelings that the two tongues are creating as they tug on my lips, tickle my clit, swirl around inside the entrance to my cunt. I try to delay it as long as possible but I am coming. I can feel my body grasping at their tongues as the waves of pleasure course through my body. But I have to push them away, my clit is too sensitive for any more attention right now. Two men can wear a girl out pretty quickly but it is great to have so much undivided attention.

Glenn sees a clock and leaps up suddenly. He has to drive back tonight and so he needs to get going. I pick up the padlock off the bedside table and pass it to Glenn. As I lie back, he clumsily tries to find the piercings in my labia. Finally he manages it and I hear the padlock click shut again. Once again only Paul has the cunt-key.

**

To my surprise I'm having a pretty normal day today. Everybody is no longer looking at me weirdly. I've not unexpectedly made out with a woman. I've not had a threesome. In fact I've not even masturbated. I'm walking across campus on my way to Paul's next woman-only calculus class. I'm wearing a skirt and no panties because...well, because I can and because I'm pretty sure most of the other women in the class won't be being shy and because I like the feel of the padlock as it tugs on my lips as I walk.

We are all sitting in the lecture theatre when Paul walks in. He is holding a hazel switch as if he is going to be water divining. I have a pretty good idea what he will be doing with it, which gives me an advantage over the other girls. Some of them might guess that their bottoms are vulnerable. I doubt many realize that they won't be allowed to keep the protection of their skirts. I realize that my fantasy from two nights ago might turn out to be pretty accurate.

Paul starts to go over the next part of the course. The integral of a product is the first times the integral of the second minus the integral of the integral of the second times the differential of the first. It's no wonder nobody can learn this stuff without the incentive of a painful whipping on their bare bottoms. As Paul talks he points to the equations on the whiteboard with the slender rod.

After about half an hour he hands out a sheet of paper. I'm not the least bit surprised to find that it is a ten-question test on the material we've just covered. Paul explains that he won't have time to deal with every woman in the room, we'd be here all night, so he will pull out four answer sheets at random. The punishment is three strokes with his switch for each wrong answer. Whoever is selected is a surrogate for everybody else. But this isn't Survivor and there is no immunity next week just because you were punished this week.

Once everyone has filled out their answer sheets he collects them. He shuffles them and picks one at random. It turns out to be a very tall thin black girl, originally from Senegal if I had to guess. He summons her to the desk at the front of the lecture hall. The room is totally silent, you could hear a pin drop. She's actually pretty good, she has the first eight questions correct. I'm rooting for her to get one wrong, I always did and besides, I want to see her naked ass. Paul tells her she has two wrong. She bends over the far side of the desk but Paul is not going to let her get away without added humiliation. He makes her bend over the front of the desk so that her ass is towards the rest of us and we have a grandstand view. He flips her skirt up over her back. She is wearing a thong. The bright pink strip of material looks a bit incongruous against her jet-black skin. For a moment I think Paul is going to let her get away with keeping it on, after all the cane will be on her buttocks not in the cleft where her thong-strap nestles. But no, he pulls it down and it falls around her ankles. I've never seen a black woman naked before. Her lips, even her inner lips, are dark brown. But I can see a fine line of pink between them, a hint of the secrets concealed within. And, of course, her padlock is dangling there. She is clearly very turned on by presenting her Nubian pussy to the audience.

Paul raises the switch. It swooshes through the air and the sharp sound of it across her buttocks echoes around the room. It takes a moment before she feels it by which time the switch is already swooshing through the air again. She starts to cry. Paul goes quickly, much faster than he did the first night with me. But then there was only one of me. Soon the six strokes are over. We can all see the dark red welts the cane left even against her black skin. Tears are streaming down her cheeks as she bends down and pulls up her thong and lets her skirt fall back into place. Not surprisingly she elects to stand rather than sit back in her seat.

Next chosen is a blonde with boobs even bigger than mine. Defying the stereotype of stupid blondes, never mind the stereotype of women not being able to do math, she only has one question wrong. In my experience the tenth question is always so hard that I think it is impossible to get right. Paul enjoys delivering punishment and doesn't want to risk missing an opportunity.

She is wearing a pair of smart pants. She bends over the desk without taking them down but of course Paul is having none of it. He makes her undo the zip at the side and drop her pants around her ankles. Surprisingly she's wearing very unsexy white underwear which soon joins her pants on the floor. She bends over. She has a really hairy sex, unusual these days when most people shave or at least trim their pubes. They are black. I'll bet she's not a natural blonde (maybe that explains why she isn't stupid. Just joking, all you blondes). Paul delivers three quick strokes and her pale white buttocks are soon striped with three angry red lines. She's tough as well as smart, managing to keep her tears in check. She pulls up her panties and her pants and walks back to her seat and, can you believe it, she sits down. I'm impressed, I have to admit. I could barely sit down for days after my caning, although admittedly I got more wrong and ended up getting nine strokes, I think it was.

We are all on the edge of our seats, of course, as Paul selects the next answer sheet. It is really arousing watching somebody get punished on our behalf, but none of us wants to be the next woman reduced to tears under Paul's merciless switch.

The next one is a Japanese woman. She is small, and like many Asians looks much younger than she must be. In fact she looks about thirteen. She walks up pretty confidently, maybe she thinks she got them all right. But no, impossible question 10 gets her. She's pretty feisty though. Before she is even asked she bends over the desk. She's actually so short that her ass isn't stuck in the air like for the previous two women. She flips her skirt up over her back. She isn't wearing anything at all underneath. She looks like a child about to be spanked, especially since she has a shaved pussy or maybe she is just naturally almost hairless. But Paul is completely equal opportunity. Black, white, Asian, everyone gets the same punishment. The first stroke falls across her ass and she screams out in pain. It's a good act, or maybe it's genuine, but it has no effect on Paul. The second stroke falls almost immediately. She's crying copiously by the third stroke. She stands up and her skirt falls into place and she walks back to near her seat and remains standing. The confidence with which she walked up is all gone. A butterfly broken on the wheel springs to mind.

Paul pulls out the next answer sheet and it's mine. Shit. I thought he'd protect me from this since I've already been through this. Or maybe he wanted me deliberately since I'm his special slave. Or maybe it was just chance, who knows. I've got three questions wrong, the worst of anyone so far. This is going to be painful. I know I won't be able to stop myself crying like a spoiled toddler. I walk up to the desk. Should I be confident or submissive? After all I know what I'm about to go through and most of these girls do not. They've never been caned in their lives, not even smacked probably. I bend over and flip up my skirt. This bit I love, bending over showing my ass and my pussy to everyone, knowing that this whole thing is something I started with my original visit to Paul's office where I flashed my tits at him. But my reverie is interrupted by a searing burn across my ass. I manage not to start crying until about my third stroke but it is so painful that I lose count and I'm surprised when I've already had nine strokes. I know my ass must look like a grid of red wheals like last time (I looked in a mirror, if you must know). I stand up as proudly as you can with tears streaming down your face and walk the few paces back to my front row seat.

I don't even get to decide whether to try and sit down or not because the evening is over. Same time next week.

**

I'm not going to tell you about every week, that would be boring. Paul mixes the punishments up and by the middle of the term most of the girls have been chastised at least once. But it definitely seems to work, you can tell that these girls are really working at learning their stuff so that they don't get punished too severely, just like I did the previous semester. Paul doesn't seem to show much mercy. You can tell from his hard cock bulging in his trousers, which he does nothing to hide, that he enjoys schooling whichever women get selected each week as much as they do not. I've stopped having private lessons with Paul since we have these group ones. That's not to say that I don't occasionally go over there for a fuck. I'm one step ahead of most of the other girls. They haven't been fucked all semester since only Paul has their cunt-keys. There's a three-day weekend coming up, one of those President's birthdays that everyone forgets about because most people don't get the day off work. Paul has given everyone an extra incentive. Anyone who gets 3 questions or less wrong gets to be unlocked for the holiday weekend. A whole 3 days of sex and fucking and real honest-to-god penetration, before their cunts are re-locked the following Tuesday. You can bet that everyone is working harder than normal. I am too. If I get unlocked then maybe I'll go home and see Glenn.

When Paul arrives the room falls quiet. Everyone is taut with suspense asking themselves the same questions. What will today's punishment be? Will I be one of the four women selected for punishment? Will I get 3 or less answers wrong and so get to be unlocked and fuck this weekend?

Paul reaches into his bag and puts something on the front of the desk. It is a black butt-plug. A small one, maybe an inch across. Then he gets out another one. This one is bigger, both fatter and longer. Another, larger still. This is shaped more like an ace of spades. The fourth is bigger still, shaped with a sort of screw thread. The room is completely silent now as every girl in the room is imagining having that monster screwed into their ass. He carries on until his tenth plug is about a foot long and about four inches wide, the size of a wine bottle but shaped differently of course. I know that the later plugs are not really intended to be used, nobody actually gets all ten questions wrong, but they look incredibly intimidating all the same. Paul doesn't need to explain the plugs, we all know that we have to take the plug that corresponds to the number of questions we get wrong. One or two would even be fun, but beyond that the plugs look like they will be painful.

Do you think everyone on the course has tried anal sex by now? I do. Sometimes just licking and sucking isn't enough, you need real penetration. And if your cunt is locked up there is only one place for a cock to go. So I reckon none of us are completely ignorant of what it feels like to have something large up our asses.

When we finally have done the test, Paul marks all the answer sheets and we all wait, hoping that it won't be us selected. I can feel my asshole spasming in a mixture of fear and excitement. It turns out that Paul isn't going to put the plugs in. Instead, whoever is selected, the two women on either side of her have to come up to the front too. The first woman is responsible for preparing the victims asshole with her tongue and the second woman is responsible for inserting the plug. Thank goodness I don't get selected today, but the girl beside me does. She has four questions wrong, so she is already pretty upset since she won't be fucking this weekend. The three of us go up to the front of the lecture hall.

Paul insists that the victim strip naked and then climbs onto the desk on all fours. Her ass facing the audience, of course. She's a rounded girl, not fat but curvy with big breasts and a big ass. She climbs up onto the desk and positions herself on her hands and knees. Her big breasts hang down underneath her body. She moves her legs apart. Her ass is pretty much at my mouth level. Even her outer pussy lips are fleshy and rounded, just like the rest of her body. Her skin is tanned, except for her ass and breasts which obviously have never seen the sun (Why is a suntanned woman like a chicken? The white bits are the best. Haha). I part her cheeks. The skin around her asshole is a darker brown and her asshole is a tight pucker deep between her Rubenesque cheeks. I bend forward and gently lick it with the tip of my tongue. As I gradually work my tongue-tip into her ass the other girl is putting lube on the huge black screw-in butt-plug. Her ass is relaxed enough now that I can easily push in a finger. This both pornographic and intimate at the same time. Who'd have thought I'd be at the front of a lecture hall with my finger fucking a strange girl's ass. She's even pushing back against my finger, enjoying it so far.

Paul makes me stand up on the desk with one leg on either side of the girl so that I can easily bend down and spread her cheeks wide. The girl with the plug takes the point and pushes it into the victim's tight hole. It goes in easily at first, I did a good job preparing it (hehe). The wider part is where the screw thread begins. I pull the cheeks as wide apart as I can. The plug girl starts to turn it. From my close vantage point I can see it gradually distending her asshole as more and more of the plug vanishes from sight. I can sort of feel the girl between my legs is incredibly tense. I know I would be. I know she'll have her teeth clamped shut to prevent herself crying out at pain, not to mention the indignity of her position.

"Masturbation can help," Paul says to the victim quietly. She reaches back underneath herself with one hand and pushes a finger into the cleft between those thick fleshy pillows while slowly the plug is screwed further into her resisting body. If the plug is pushed too hard then the girl tenses up in pain. Her whole body, including her asshole, goes rigid. So it is necessary to go slowly enough that she can keep the pain under control and her ass relaxed enough. Finally the thickest part of the plug enters her and the rest of the plug goes in easily as her ass muscle clamps onto the narrow neck near the base.

I realize that the girl crouching between my legs is starting to come. She's still masturbating her clit in its fleshy home. I can see her body convulse, I can even see her asshole spasming on the enormous black plug incongruously locked into her back entrance. I look up at the audience. Many of the girls are touching themselves, some surreptitiously and some quite blatantly. It must look really sexy, especially when everyone is so glad it is not them.

Paul indicates to remove the plug and so I pull the cheeks wide apart again while the other girl pulls the plug out. It resists at first as the widest part has to go back through the ring of muscle and then it slowly emerges.

After that the rest of the evening is an anticlimax since the other girls selected only have 2 or 3 questions wrong. So they are happy for having a weekend unlocked and the smaller plugs look like nothing after you've seen the number four plug violating a young girl.

**

You are probably wondering what's going to happen the last session of the semester. So am I. I've not said anything to anyone about how when I was being coached one-on-one Paul switched to multiple orgasms for the last session. I'm hoping he'll do it again, of course.

So here we are on the last chapter of the textbook, particular integrals and complementary functions. Most of us would have had no hope of passing this course without the extra ‘encouragement' that we have been given to learn. Me included. Our bottoms may be marked from punishment, our nipples and assholes may be sore, our cunts are locked up, our clits are raw from over-use but we know lots about integral calculus.

When Paul arrives he says nothing about punishment. He doesn't seem to have any props with him: no cane, no whip, no nipple-clamps, no butt-plugs, no gags, nothing electric. The class proceeds normally until Paul hands out the ten question sheet at the end.

"Firstly," he says, "I want each of you to come up here, strip naked, and I will remove the padlock from your pussy. Unlike in previous weeks, I won't be making a random selection of your answer papers, you will all get the treatment appropriate to your marks.

"For the first question you get wrong you must masturbate to orgasm. For the second question you must find a partner and have her stimulate you to orgasm with a finger. For the third, with her tongue. For the fourth she must fuck you until you come with a strap-on cock. And if anyone is foolish enough to get 5 or more questions wrong then she will have to fuck the strap-on while her ass is whipped." Paul unthreaded the thick leather belt from his belt-loops and laid it on the desk. It was made of raw hide and looked rough and heavy and definitely painful.

"Oh, and one last thing. An additional incentive. One of the women who gets the least wrong will be selected at random and I will take them home tonight."

Wow. Every woman in the room will want to fuck Paul tonight. It is hard to exaggerate the desire for a master that being a slave can generate. And we are all Paul's slaves with our pussies locked up for his pleasure, our boyfriends restricted to our mouths and our asses.

You'd like to watch this scene wouldn't you. A couple of dozen attractive women naked and making each other come in different ways. There's already a group of people at the front desk. A few naked ones already have their cunts back, Paul is unlocking the padlock from the prominent lips of a cute Chicana with a slim boyish figure. I wouldn't say ‘no' if you know what I mean, hehe. The next girl, the tall black woman who got the first punishment that first day, is peeling off her clothes and behind her is a line of still-dressed girls where I'm somewhere in the middle. To tell the truth I don't really want my cunt back. I'm used to being Paul's slave. Even sex with Glenn was so much hotter because Paul was watching (well, a bit more than watching, I know).

It's a bit later. I got three questions wrong, so after masturbating I managed to pair up with the cute Chicana. She's a Mexican who only came here a couple of years ago. I bet she's never done anything like this before. She may not have perfect English but her finger is between my lips and just teasing my clit and she knows exactly what she is doing. She opens her legs for me and I slip my hand across her belly. She has a very boyish figure, not curvy, tiny breasts. She has just a small patch of sparse black hair like a small moustache. I run my fingers through it feeling for the divide of her sex. She moans as my finger slides into her slit and first touches her clit. It's not part of the program or anything, but we start kissing as we play with each other's clits. She's got me just short of coming. I think she wants to make me come with her. She's pretty close too. She's closed her thighs tightly over my fingers, squeezing it harder against her clit, so she's almost fucking my finger with her pussy lips. She's squeezing so tightly it is almost painful on my hand and then she relaxes as fireworks go off inside her. Her body is covered with a very fine sheen of sweat. I come just a few seconds behind her, a nice orgasm but nothing as spectacular as hers looked. We lie down in a sixty-nine on the lecture room floor. Her pussy has really big thick inner lips that it is fun to suck into my mouth and she has the biggest clit I think I've seen Not that I've seen that many up close, of course. It sort of sticks out from between her lips like a tiny hard penis head. I don't waste any time before I'm licking her out, my tongue in her taco, as it were. Her tongue is in mine too, of course. I can feel her fingers opening me up like an oyster to better get at my soft tasty center. The whole room smells of sex. There must have been at least fifty orgasms in here in the last half-hour. I am close to coming so I stop licking her and shut my eyes so I can concentrate on my own pleasure for a moment. She really knows how to lick a pussy, which is unexpected. I'd be surprised if she got any practice in Catholic Mexico. I enjoy the feeling of my orgasm building up inside my body like a string stretching towards breaking point. And then it snaps and I'm coming and my body takes over my brain and it is like a huge lightning storm. I close my legs and push her away, my clit is too tender to take any more. I open my eyes and there are her meaty crimson lips and her little penis clit. I suck her whole pussy into my mouth and play with it with my tongue. She is whimpering with undiluted joy. I'm getting pretty good at this pussy licking, don't you think? I can feel her hard clit in my mouth and I very gently close my teeth on it. She squeals in surprise. I tickle the head of her clit with my tongue as I tenderly bite her. I can tell it is almost too intense for her, so exciting but borderline painful. But I don't let up, I bite her slightly harder as her climax begins and then I back off completely, just kissing her pussy lips softly as the waves of delight sluice over her. "Gracias," she murmurs.

Everyone has finished their ‘punishments' now. The course is almost over. Well, we have a final exam tomorrow but that's pretty much a formality. Paul announces that there were only three people who only got two questions wrong, and after selecting one at random it is Natasha. I know her from several other classes. She's a bit snooty (but I have to admit she's really smart). I always thought she had a killer body when I saw her dressed. Now that she is naked, it is incredible. Long legs leading to a beautiful curvy ass. Waxed completely smooth. Nice breasts, smaller than mine but with big pointed crimson nipples. She is slim with an hourglass figure. She has long brown curls. Paul is going to have fun tonight, I know. But wait, he is walking in my direction. "Come to my place when you leave," he whispers to me casually as he passes.

**

I arrive at Paul's house. I have a key. Funny, isn't it? I have key to his house but not to my cunt. Well, it is unlocked right now, I know, and I'm pretty sure Paul's cock will be in it before the night is out. I let myself in. The living room is dark and I go back to the bedroom. Paul is just finishing attaching a rope so that Natasha is tied to the bed face up. She is blindfolded.

"I'll get you a glass of wine," Paul says to me. "Why don't you have the first taste?"

As I told you, she's very beautiful. Look at her waxed-smooth pussy. See how her inner lips are like a large pink butterfly with its wings symmetrically splayed out to either side of her slit. How come a beautiful woman like Natasha even has a beautiful pussy? I haven't a clue if she even knows who I am when I kiss her gently. Maybe she doesn't even know if I'm a man or a woman. Her lips are soft and I pull on them gently with my teeth before kissing her harder, seeking out her tongue with mine. I look down at her breasts. I have to kiss them too. They are so firm, standing up proudly like small hills, her areolas like conical crimson castles on top, with those long nipples that are soon in my mouth. She's obviously one of those women with really sensitive nipples because she starts to squirm as I kiss and nibble and tongue her nipples. She can't squirm much, of course, since she's tied to the bed. Paul comes back in and hands me a glass of champagne. I take a sip and then bend forward and kiss Natasha, feeling her surprise as I let the fizzing liquid dribble into her mouth. I take another big mouthful and kiss her again, our tongues playing with each other as the champagne pops and bubbles around our tongues. I move down the bed to that beautiful butterfly pussy. I can see nectar of her arousal where it seeps from her pussy and runs down towards where her asshole nestles out of sight. I smile to myself about how perfect her body is. I bet that even her asshole is beautiful, a perfectly symmetrical circular pink rosebud.

I take another mouthful of champagne and this time I let it dribble onto the crack of her sex and run down over her clit and her lips. She squirms again with surprise at the unexpected touch of the ice-cold sparkling liquid. Another sip and I press my mouth to her clit, not really touching it, just letting the champagne effervesce all over it. I move up the bed and squat above her face, holding on to the rail at the top of the headboard. She can smell me but I'm still too far away for her tongue. If she didn't know if I was male or female she does now. I lower myself so my pussy just touches her lips. I watch as her tongue slithers out like a hunting snake and disappears around the curve of my body and into my slit. Mmm, that feels good. She's got a really long tongue, I can feel it right up inside me as I sit on her face.

I hear Paul's clothes fall to the floor so I move back down Natasha's body slowly until I'm on all fours between her outspread legs in front of that pretty pink butterfly of a pussy. As I lower myself to lick her, I spread my legs for Paul who is standing at the end of the bed. I can't see him but I'm guessing his cock is hard since I know he loves to watch two women having sex together. I run my tongue up and down between the pink wings. She tastes sweet. I can feel Paul's cock at my cunt so I push backwards as he enters me. I start to fuck Natasha hard with my tongue, thrusting my whole body back and forth aggressively. When I move back I ram my ass hard against Paul's body, burying his cock as deeply in me as I can. Then I move forward and run my tongue over Natasha up between her lips and over her little grape-seed sized clit. I move one of my hands and slip a finger into Natasha so that my finger slides in and out of her in time with Paul's cock in my cunt. I let another finger drift lower so I'm stroking her asshole at the same time. Paul is fucking me really roughly now, just how I like it. I just have to push my tongue against Natasha's pussy and each hard thrust of Paul against my ass knocks me forward onto her. It's as if Paul is fucking us both at the same time. We carry on like this for a little while since we all know Natasha is close to coming. My tongue is right on her clit now and Paul is fucking me hard and fast. Natasha is almost screaming on each thrust, who knows what the neighbors must think. And then she is panting and moaning and coming, thrusting her body back and forth against the bonds that hold her immobilized on the bed.

I think it is time for Paul to fuck Natasha's butterfly, so I grab a couple of pillows and push them under Natasha's butt so that she is now not just spread-eagled but her hips are raised higher than the rest of her body so that Paul can enter her easily. I lean over and lick Paul's cock. I can taste myself on him. When his cock is good and wet with my saliva I guide him into Natasha's opening where my tongue has been playing. She groans as Paul works his wide cock into her tight hole. Paul starts to fuck her in long slow strokes, going from his cockhead coming right out of her before sliding back in as deeply as possible. I move and lie on my back between his legs so that I can lick his balls as he moves in and out of the fissure in Natasha's perfect crotch. He pulls out of her and lowers his cock into my mouth. I give him a few licks and then reposition him back in Natasha. This way we can share him until we make him come. That's the trouble with a two girl threesome, we need a man who can come lots of times like us.

I move out and let Paul finish off fucking Natasha. I can have him anytime. I sit down and drink some Champagne as I watch my master fucking a beautiful woman. It is my own porno movie. I bet Natasha in War and Peace never enjoyed the ball as much as this Natasha is enjoying being balled. I think Paul is getting close to coming, he lies down onto Natasha and kisses her, pushing her pointed breasts against his chest as his hips thrust up and down between her outstretched thighs. He pulls out of her and moves up the bed and lowers his cock into her mouth. The timing is perfect, the first squirts of his orgasm arrive just as she closes her mouth around his knob. She licks him as his balls empty themselves into her mouth.

We untie Natasha and all get into bed. There will be time in the morning, or maybe even later tonight, for more leisurely love-making. I wrap my arms around Natasha's soft body, a hand on her breast and my breasts squashed against her back. I can feel Paul's limp cock at my ass and the length of his body pressed against my back. I'm the filling of a lovely sandwich. Soon the three of us are asleep.

**

It's a sunny morning. We've had another play with Natasha's perfect body but she has had to leave for her class. I will have to go too, soon. I get up and have a shower. Yes, I shave my lips too, if you must know; it's a lot easier than normal without having to avoid the padlock. I walk back into the bedroom. I feel really naked without feel of the weight of the padlock (and, yes, I do realize I actually am naked).

I walk over and stand beside the bed and move my feet a couple of feet apart. On the bedside table I can see both the new padlock that was removed yesterday evening and also the larger, heavier one that I originally wore. I pick up the original one, my special lock, the one that launched this whole episode of my life. I reach between my legs and grab my left inner labia (or is it labium, who knows?) and thread the hasp through the pierced hole. Then I pull my right lip taut and thread the hasp through the second hole. There is a loud click as the padlocks closes. I am Paul's slave once again. Only he has the key to my cunt. His eyes follow the small lock as it sways gently between my legs, reminding me of its presence as it gently tugs my lips.

**

You are wondering if I am going to do any more math classes, aren't you? Since I'm majoring in elementary education it's not as if I'm going to be teaching my kids any of this stuff. But I have to admit that ‘differential equations' is looking more and more attractive. Or how about ‘Maxwell's equations.' I've no idea who this Maxwell guy is, but I do know that Paul is the professor for the class. Or I could lose my padlock and have a nice normal relationship with Glenn without any threesomes or lesbian sex or punishment. But that would be boring, wouldn't it?