When I was studying at College I lived with a couple called Sara and Mike whose bedroom was next door to mine. Some nights I would us listening to their conversations through the wall. Of course it wasn't the conversations that i was interested in.
Some nights when I heard a few creaks in the bed, I would slowly climb out of my bed, out of my room and stand just outside their door and listen with my hand wrapped around my dick and slowly massaging it.
Whenever I started to hear Sara's heavy breathing then I knew that was my cue to remove my pants leaving me completely naked outside their door. I guess she was receiving oral sex because after the breathing she would say something like 'fuck me now' in a hushed voice which really turned me on.
Then when Sara started to groan and scream out loud that's when I started to masturbate furiously before they finished (mike never lasted long). Eventually I would cum outside the door, leaving it there and climb back into bed.