I jerk off when I hear my roommate having sex with this girl. They usually have music on but I can still hear the creaking in the bed and the moans. They try to be discreet but right at the end I can hear his girlfriend start grinding out "o fuck me I'm going to cum.. " and bro just starts pounding it. I try to time it with them. Fucking wish one day they'd invite me to participate but I don't think they're into that. Another lifetime maybe.