Remember in "Rain Man" when Dustin Hoffman overheard Tom Cruise and his girlfriend having sex? He walks into the room and stands at the foot of the bed, and starts grunting like Tom Cruise until they overhear him. The guy is the loud one? WTF is up with that?
In my opinion, talking to the roommate is the best idea too, that's why I +1'd Indy's post. My other suggestions were just jokes. Although, if the roommate was spoken to and continued to carry on the loud sexing, I would totally do the soundtrack thing
Haha. He could explain "WHY" he's doing the things we've suggested, as he's doing them. That way, it wouldn't be passive-aggressive at all. Maybe that would be more appropriate. Of course, after he's spoken to the roommate about the situation.