I (M) caught an undergraduate (f) having sex in my lab.

Years ago when I was in graduate school I’d have to often go into the lab at nights to make sure my yeast cultures were taken care of properly. This happened pretty regularly, but I usually tried to arrange it so that my Friday and Saturday nights wouldn’t be all screwed up by having to go in and feed a bunch of single celled organisms. I remember having to do this one absolutely beautiful late spring day. Spring in New England can drag on through months of cold and rain, so I remember being particularly frustrated that finally it was nice and yet again I’d be stuck inside.

My questioning my career choices as I walked over to campus and into the lab building isn’t really really here. When I got up to the lab the lights were on though, which they should not have been. I entered through the side door near the big flask shaker thing, which was quite loud, and I immediately hear people having sex. I pause and stop walking into the room. I’m still in the entry hallway area so I can’t see them, but I can hear them clearly. The usual college kid dirty talk, her moaning and complimenting his cock, etc… I do recognize her voice though – she’s an undergraduate that is also doing some research in the lab, and has stayed over the summer to do more research. She’s smart and does great work, unlike most of the undergrads. She’s also fucking hot – toned body with nice breasts, smooth tanned skin, a very pretty face with long brown hair and eyes. The guy who’s fucking her, whom I do not recognize by voice, is very lucky.

I stand there listening, and I realize I’m getting quite hard listening to her get fucked hard by this anonymous guy. I imagine what she might look like nude, lying on a bed in front of me and about to have my cock enter her. I wonder if it’s inappropriate to be listening to them like this, eavesdropping on this private moment as I now absentmindedly stroke my cock through my pants. No, I remind myself, they’re actually not supposed to be in here and you are.

I should actually go stop them, and if I happen to see her naked that’s just a nice bonus. The feeding is time sensitive after all. But then it sounds as if she’s about to cum. Ok, I’ll give them a brief while longer in that case. My hand is down my pants at this point, just stroking my cock while I lean against the wall listening to them. I hear her cum and think that it’s time to put an end to this and get to work.

I walk out into the lab, and see her leaning against one of the lab benches with him fucking her from behind. She’s wearing what I think is a blue and white sundress, though it’s all bunched up at her waist. Her breasts are amazing looking, large and perky with dark areolas. She’s got toned, long legs that lead up to her firm ass. The guy’s not bad looking either, and I can see he’s got a decent sized cock sliding in and out of her pussy.

“Uhm, hello there,” I awkwardly say to interrupt them. I’m standing maybe twenty feet away from them, but they didn’t notice anything until I spoke up. “I need to, uh, feed some of my cultures now.”

“Shit,” she exclaims. She seems very surprised and stands up to face me, causing the guy’s cock to fall out of her. One of her hands brushes her hair away from her face so she can see better while the other starts to pull her dress up. I have a nice frontal view of all of her for a moment though and see the narrow strip of dark hair above her pussy. “I’m so sorry,” she adds as she pulls up the straps of the sun dress and covers up her breasts.

“Fuck,” the guy shouts. He seems kind of pissed, which makes sense because I just stopped him from cumming. He pulls his condom off his now flaccid cock and throws it in the wastebasket next to a desk. “What the fuck are you doing here?”

“I’m feeding my cultures,” I say gesturing over to the loud shaker on the floor. “This is a lab. People come here at all hours to deal with this stuff. Don’t get mad at me. There’s also lots of nasty stuff in here that you really don’t want on your skin. And the guy who’s bench your fucking at isn’t know for his cleanliness.”

“I’m sorry,” she says even more apologetically now. She’s fully dressed again, though without panties. Maybe she hadn’t worn them when she came out? He’s pulled his shorts back up too. “We were just looking for someplace private. We’ll go now though.”

“It’s fine,” is my response as they head out the door. She keeps apologizing as they leave and he mumbles something and nods to me as they exit. That was a bit more excitement than I was expecting. I start thinking of her naked body, now knowing exactly what it looks like, as I start to gather supplies for my work.

About five minutes later she walks back into the lab. She’s far more composed this time, what with her having all of her clothes properly on. Her long dark hair is also now pulled back in a ponytail. “Look,” she says, “I’m really sorry for what happened earlier. It was a bad judgment call on my part, but I’d really appreciate it if you didn’t report it to the professor. I’m happy to help you finish up tonight so we can both get out of here.”

“Oh, don’t worry I’d never tell him anything,” I say to her as I shrug and gesture for her to help. “I don’t really care if you fuck in here, but it does seem not the best place. It’s a biology lab, run by people who are lax about following safety precautions.”

“Thank you,” she says as she helps with the yeast. With the two of us working on it we’ll be finished in just a couple of minutes. “Both of our roommates were around tonight and, well, you know…”

“I get it, but this isn’t the right place for that,” I say as I start to clean up my work. I pause briefly before adding, “The conference rooms up on the 4th floor though, those would work well.”

She smiles for the first time I’ve seen her tonight, suddenly relieved that she’s not at any risk of being in trouble. “Is that where you go to fuck Amanda when you’re both working here late?”

“I guess that’s not as secret as we thought”

“No,” she says with a soft laugh.

“Well that’s where you can go. You have the same access that I do, so you should be able to get in there without any problem. Fuck on a cheap conference table. Just don’t be a dick and clean up when you’re done.”

“I don’t actually know where those rooms are. Can you show me?”
“Sure,” I sigh now that we’re finished with the work. I’m tired at this point and the brief excitement has faded and I just want to go home. “Let’s go up there and then we can head home.”

We walk on up there and when we reach the door I gesture for her to swipe her ID. It works fine and the door clicks open. I walk in and turn the lights on and gesture around the remarkably dull looking room. “See,” I say, “windowless and perfect for afterhours fucking.”

She closes the door behind her and walks over to me. She has a look on her face that is hungry maybe? Whatever it is, it’s a very hot look and is making me hard again. I remember what she looks like naked again as she walks towards me. “This is perfect. I should thank you for pointing it out to me.”

Now her one arm is draped around my shoulder while the other goes straight to my cock, rubbing it through my jeans. I look down at her face, so eager to please me. I look down at her breasts, looking so nice beneath the thin fabric of the sundress. “Oh, you don’t need to do that.”

“It seems like you want me to,” she responds. Now her fingers are undoing my fly and pulling my pants down. My hard cock pops out quickly, dripping precum out the tip. She takes it in her hands and strokes it gently. She tilts her head up to me and kisses me, her breasts pressing against my chest.

Fuck it, I think to myself, no way I’m not going along with this. I push the straps of her sundress of her shoulders and start caressing her beautiful breasts. Feeling how stiff her nipples are becoming in my fingers as she kisses me and keeps stroking my cock. She steps back and pulls her dress up over her head then, standing in front of me completely naked. I have a better view of her now, all of her damn near perfect body in front of me. I pull my shirt off along with the rest of my pants so that I’m nearly equally naked in front of her, though significantly less of a perfect body.

She kneels down in front of me and takes my cock in her hand again. She licks it with her tongue while looking up at me. “Fuck, you are so beautiful,” I moan. She smiles at me as she starts to suck on one of my balls. I run my hand through her hair and grab her ponytail lightly. A feeling that this is all very unreal enters my mind, but I push it away and enjoy the moment as she takes my cock in her mouth. Her fingers move back toward my ass and I feel her starting to finger my asshole. The way her mouth feels on my cock combined with her playing with my asshole, and her being so attractive make this easily one of the best blowjobs I’ve ever had.

She stops sucking my cock and leans back on her knees and looks up at me. I take my cock in my hand and stroke it while looking at her. Thinking about cumming and watching it shoot all over her breasts and pretty face. Then she stands up and presses against me again, kissing me while my cock rubs against her stomach. I reach down and grab her ass, then slide my hand between her legs to feel her pussy. She’s so fucking wet as I turn her and press her up against the cheap conference table. I caress her breasts a bit as I push her ass onto the table. Her arms are around my neck as we kiss some more and I can feel my cock brush against that narrow strip of pubic hair, and my balls rub against her wet cunt. “Have you ever fucked two guys in one day?”

“I have not,” she says with a smile. I reach down and I’m rubbing the shaft of my cock against her wet pussy lips. I brush the tip of my cock against her clit, then down across her lips and to her inner thigh. “I think it might be fun though.”

She’s biting down on half her lip with a partial smile now. I guide my cock back towards her pussy and slowly push it into her. She moans a bit at that first moment of penetration. That initial moment is always my favorite, just feeling how wet and tight she is for the first time. Slowly working my cock deeper into her with each thrust. I bring my hands to her hips and to help as she leans back on her arms, moaning loudly as my cock penetrates deep into her. It’s an amazing view for me – her lying back naked on the table like that with her legs spread, giving me a great view of her breasts and all of her tanned body. As I watch my cock sliding in and out of her shaved cunt I think back to how I imagined her nude 30 minutes earlier and how it’s even better now.

She shifts her position a bit, lifting her left leg up and putting it on my shoulder as I lean in over her. “You like my cock in you,” I ask her as I kiss her neck. I move down and kiss her breasts, moving my tongue over her stiff nipples before I take them in my mouth and suck on them a bit. I hear her moan loudly as I fuck her.

“Mmm, yes it feels so good,” she sighs. Her hand moves to her breast and she starts to massage them herself. Tweaking her nipples between her fingers. Then moving down to start rubbing her clit. I lean back again and watch her. Her moans and sighs, the way her body is starting to shudder a bit. I pull her hips closer to the edge of the table and push my cock deep into her as she cums hard.

She’s loud too. And it’s at that moment that I think that while nobody can see us here, they could certainly *hear* this. Oh well.

I pull her off the table and turn her around in front of me. She leans against the table and sticks her ass out a bit. I push my cock against her then slide it between her ass cheeks and thrust gently. I push it back down and rub it against her smooth pussy lips before entering her again. I grab her hips again and pull her onto my cock. Looking down I see the faintest hint of a tan-line on her ass, then watch as I see my cock moving in and out of her, covered in the juice of her wet pussy. I pull her up and lean against her, reaching around so I can grope her breasts. “I want to fill your pussy with my cum,” I whisper in her ear.

She leans down against the table again, and looks over her shoulder at me. “Do it,” she says. “I want to feel you cum inside of me.” I grab her ponytail from behind and sharply pull her back towards me. I feel my cock deep in her as I grab her breast with the other hand and cum hard inside of her, grunting in her ear as I do.

I push her back down on the table and rest briefly on top of her before backing away and standing up straight. She turns around and leans against the table and reaches over to grab the box of tissues, using a fistful of them to start cleaning up a bit. We both get dressed up again quietly. When we’re both ready to go she turns to me and says, “Thanks for showing me this room. I’ll definitely come here the next time I need a private place to fuck my boyfriend.”

Source: reddit.com/r/eroticliterature/comments/mdw6j9/i_m_caught_an_undergraduate_f_having_sex_in_my_lab