In second grade I was obsessed with Legend of Zelda: Ocarina of Time. I played it so much that sometimes I thought I heard the Lost Woods song(look it up) playing. It would be silent in the classroom and I'd be looking around trying to find where the hell the sound was coming from. I was convinced another classroom was playing it for some reason.
Also, after I got my Xbox360 sometimes I would hear the *ba-dip* sound effect of people logging on.