Being so close to them made me insanely hot.
I lived with a particular male friend for several years during my late 20's. As we both were active on the social scene, it was not uncommon for us both to bring home two or more sexual partners a week. I could usually hear my friend when he got busy with his guests; he had a fat, beautiful cock (noticed during strip poker), and the intense groans and moanings it evoked from his lady friends rang loudly through the house. Most of the time, I'd just go back to sleep after being awakened by it.
One certain night, however, things began to change. I heard him come home with a girl I knew to be a bisexual. She wasn't beautiful, but her close - cropped hair, strong personality and constant bragging of performing cunnilingus turned me on outrageously. I heard them settle into bed and didn't think much about it. Soon, though, I knew something serious was beginning to happen. Her breathing was shallow and rapid, while his was heavy and slow. I began to get hard quickly.
I knew simply lying there and stroking wouldn't be enough. I crept out of bed, opened my door, and inched towards his bedroom at the end of the hall. His door was ajar about four inches. I got to within three feet, stopped, looked and listened as I pulled my cock out of my boxer shorts.
My timing couldn't have been more glorious. I could see the top halves of their bodies, naked on the bedspread. I was stroking to them as he started to finish his conquest. Ms. Strong, Confident Bisexual-Lady didn't seem as in control now, as my friend hovered over her. I could see his smug sneer as he prepared to get his thrust in.
His hips moved up and down a little as he must have been rubbing the head of his dick over her open pussy. 'That o.k.?' I heard him ask her in that smirky voice. 'Yes,' she got out (barely). She was having a hard time talking, and I was on the verge of cumming. I couldn't believe I'd gotten myself into such a vulnerable position to be noticed, visibly jacking off within feet of my roommate's door.
Then he went in fully. I'll never forget the look that flew across her face: her mouth opened wide, eyes as big as plates, and she stared in disbelief up at him. 'Oh, God,' she gasped weakly to him. 'Are you alright?' he asked her in that condescending one.
He had always been so proud of that cock. I knew then why. He really knew how to use it. As she kept trying to catch her breath, he began seriously pounding her with his cock. My own dick was so lubed up already with precum that my hand flew over it. I looked at him as he pulled out, then drove it back in to the hilt. I started cumming. Knowing that my friend's dick was the main factor in my orgasm made me blow my load across the hall and onto the wall. As the last drops fell, I slowly backed up into my own room and slowly closed the door.
Good God, that was some hot stuff.