I lived in an apartment building where my bedroom and the bedroom of the apt next door shared a common wall. The guy in the apartment next door was this quiet, bookish type. We rarely spoke beyond saying "hey" to each other if we happened to meet up. One weekend I was laid up with a cold and ended up sleeping most of Saturday away. I woke up in the middle of the night hungry and thirsty from not eating or drinking anything all day. I didn't bother with the lights and went and got a snack and was sitting in bed when I realized how quiet everything was, I also realized that I could clearly hear my neighbor talking in his bedroom. I sat there on the bed trying to hear if there was anyone else and quickly realized that he was alone. Then he moaned! Clearly it was the sound of someone having sex. I put my ear against the wall and could clearly hear him. He was talking to his cock. He kept saying stuff like " so fucking hard...yeah...gimme some of that pre-cum...yeah...fuckin' big, hard cock..."
I was hard as a rock and strokin' mine along with him. He went on like that for at least another hour. He would get up and walk around the room and even out of his bedroom into the rest of the apartment. At one point I heard him unlocking his front door so I went to mine (our front doors faced one another across a common porch area) and looked through the peephole, he was standing with the door open stroking a huge hard on. He half stepped out the door and just stood there stroking for a few minutes then he went back inside. When he finally blew his load he muffled his moans with his pillows, but from the other side of the wall it was like he was right there in my bed moaning and pumping out what sounded like a huge load.
Once i became aware of his routine I would listen to him every chance I got. I figured out that he was also into self-sucking along with some serious marathon edging sessions.
It was fucking hot!