This happened a few years ago during my senior year at school
When I was 22 and a senior in college I was working late one night in the library. It was the last project of the year in my toughest chemistry class, and my partner (Dave) and I were working late in a private study room.
Dave and I had been working together since we were sophomores, so we were pretty good friends. In fact, it was our previous relationship that sort of made this happen.
We'd been working for a while and it was very late, 1 am, but we were far from done. I was fidgeting in my seat and Dave looked over and said, 'Are you ok?' I responded that I was ok, but then changed my mind. 'Hey, we're pretty good friends, right?' I asked. 'Yeah, we are,' he responded. 'Well, ok, if I do something do you promise not to laugh or tell anyone about it?' I said, putting my hand on his arm from my chair. 'Sure, your secret is safe with me,' he said and with that I smiled, leaned to the left in my chair and let out a long, loud fart. Damn it felt good, I can't even describe how good. And I wasn't the least bit embarassed about doing it in front of Dave. I'd been holding it all night and didn't know if I could manage it for the rest of the night. He just smiled and asked if I felt better. 'Yes, I do, but I'm sure there'll be more. I hope that's ok,' I said, straightening my skirt back out in my seat. 'Yeah,it's cool,' he said with a chuckle.
We went back to work and I must've farted at least 4 more times in the next 20 minutes. I was kinda blushing and he was just smiling at me, but we weren't really talking about it. They felt so good, I was much more comfortable working now.
But now Dave was kinda fidgeting and I glanced over and noticed a tent in his trousers! Smiling and emboldened, I put my hand on his thigh and looked down at his bulge. 'You seem uncomfortable, Dave,' I said and he looked at my hand and his crotch. 'What's gotten into you?' I asked. He laughed awkwardly and said he couldn't help it. I asked what it was that got him so hard and said 'When you farted.' I was shocked! My noisy butt had made this guy so hard! I couldn't believe it, but was so turned on I went with it. 'Well,' I said, 'I'm going to be farting more all night, I can tell. But if it's going to make you like this so you can't concentrate, then we ought to do something about it. Why don't you rub it out so it isn't a distraction?' His eyes got wide and he asked if I meant him to do it right there in front of me. 'Well of course. Besides, if me farting turns you on, it'll probably help you come faster if I do it while you masturbate.'
With that, he looked around the windows of the private room and saw no one around. He unzipped his pants and pulled out his very hard, very impressive cock. It was huge and I was so thrilled to get to see it. It must've been at least 7 inches long and pretty thick. He started rubbing it gently at first while I watched him intently from my chair not but 2 feet away. He used his left hand on his balls when I felt another fart on the way out. 'Another one's coming,' I said, just before leaning to the side again and letting it out. It was loud and vibrated my seat and I could tell it turned him on as his stroking sped up. I was getting wet now, I could feel it in my panties.
'Let me see your butt,' he said between breaths. 'Do you have to fart again?'
I hiked up my skirt and turned my butt toward him, my knees on the seat of my chair. I pulled my panties down far enough to let my butt cheeks free without exposing my dripping pussy to him. I had a boyfriend at the time, so despite being misguided, my judgment told me not to let him see my pussy. His stroking sped up, I knew he was close, and I felt another fart come up through my butt. I was amazed that it turned him on so much to hear me do that. 'Oh God, I'm gonna come!' he said and stood up, shooting his cum onto the table. I turned around and got to watch every spurt of his load pour out onto the wooden table, oh my god it was sexy. I couldn't stand it anymore and as he cleaned up, I smiled and said, 'I need to go to the ladies room and freshen up, I'll be right back. That was very sexy Dave, I hope you feel better now.' And with that I pulled my panties back up and walked to the empty ladies' room and proceeded to rub myself off in the stall. I came so fast and so hard, it was amazing. My mind wandered to thoughts of what I'd just seen and how much of an effect I had on his gorgeous cock.
Newly focused, I returned to the room and Dave was there, working busily, no evidence of our escapade in sight. He smiled as I sat down and thanked me for letting him take care of it. I asked him why it turned him on so much to hear me fart and he said it wa because he'd never heard a girl do that before. We finished the project and went home. I had some of the best sex with my boyfriend that night.
I'm single at the moment and think about that night with Dave often when I masturbate.