bum flap

It is a piece of fabric about 13x13 hanging from the waist covering the butt (the front/sides)sometimes with d-rings, usually plaid or pinstripe, mostly worn by the punk community.

Girl 1: Woah, that bum flap goes great with his bondage pants

Girl 2: ... no bitch.

by LynchingNemo January 22, 2008