In college I dated a tall, lanky, sexy girl named Leigh who lived in a sorority house in a double room. Leigh's roommate Hannah was single at the time and, after Leigh and I fell asleep following hours of (carelessly) loud fooling around, I could hear the rhythmic shaking of bedsprings through the wall. I wasn't sure at first, but I soon realized Leigh's roommate was listening to us and masturbating when she thought we'd fallen asleep. Once I realized this, I started fantasizing about Hannah needing to cum and it quickly became a powerful sexual obsession. Even when I was fingering Leigh's clit, I would imagine it was Hannah's. In daylight hours, I would make conversation with Hannah whenever I was over there, she was a cute sandy blonde girl with perky tits and muscular tennis legs, but all I could think about was Hannah frigging herself. What was she imagining? Was it me that turned her on? Was it Leigh? Was it lust in its purest form?
Second semester, Leigh had a class at 8:05am on Tuesdays and Thursdays. Technically guys weren't allowed above the first floor in sorority houses at all, but Leigh would sneak out early in the morning for class so I could sleep. As soon as she left, I would imagine Hannah playing with herself and I would get rock hard. At first I was careful to stroke myself quietly, but after a couple of powerful solo orgasms, I started fantasizing that Hannah was listening and I decided to put on a show for her, rocking the bed a little, grunting softly.
About three weeks into the semester, I got braver. After Leigh crept out, I went to the bathroom (always a delicate event, other than Hannah, Leigh's sorority sisters didn't much care for my near-perpetual presence in the house) and I left the door to Leigh's bedroom open about two feet so Hannah would be able to see on her way through to the front door of the outer room. I took off my t-shirt and boxers and started stroking myself under just the thin bedsheet. My cock was so stiff and so visible through the sheet and I just left it tenting out the covers, hoping Hannah would walk by. I pretended to have fallen asleep on my back.
It seemed like hours (it was probably about 15 minutes) and my heartbeat was pounding in my ears and my cock was oozing precum all over. I kept giving myself squeezes, not stroking, just applying enough pressure to tease myself. My balls were starting to ache with built up jism. When I heard Hannah's door open, my heart nearly jumped out of my chest. Showtime. I did my best impersonation of a happy, lazy seal, basking in the sun on a rock, stretched out asleep with my cock just jutting out above me. Hannah was very shy and I wasn't sure what would happen when she walked by. I heard her footsteps pause by Leigh's door, and then a quiet gasp. And then: nothing at all. I waited a few seconds and then, just to be safe, I stretched as if I were waking up and opened my eyes slowly.
Hannah was nowhere to be found, but my cockhead was so fat and engorged I wasn't going to be able to make it back to my dorm room without release, so I peeled back the sheet and I started going at it with the door still open. I pulled down the sheet and closed my eyes and started imagining Hannah parting her pussy lips and jilling off to my motions. I was just rubbing my index finger over my wet cockhead slit, prolonging the inevitable, when I heard a floorboard creak, and I opened my eyes to see Hannah, smiling and peering through the doorway. She was dressed for her morning run in short, tight spandex shorts and a jogging bra with a cd player strapped to her shoulder and I just lost it totally and started spewing cum in wet thick globs all over the place. Her eyes widened with surprise (maybe shock) but she never stopped smiling while I finished myself in front of her.
I was simultaneously feeling triumphant and guilty and I suddenly came back to reality and recognized that I was sitting in my girlfriend's bed covered in my own cum while her roommate was looking at me...an awkward pose. Hannah handled it gracefully. She put her index finger up to her lips to shush me before I could speak and went back into her room. I heard the door click shut, the sound of spandex coming off, and then soft moans and bedsprings.
I cleaned up and got out of there, still very confused.