Who hasn't had this happen?  You go to the gym. Find a pretty empty bank of lockers where you can get changed without jostling butts with people right next to you. Go down to put your stuff away. Then look up and BAM! there's some naked old dude (or lady if that's the type of locker room you go into) trying to get into the locker right next to yours.

Anyways, I kind of just wanted to draw more butts.