What is a bum flap you ask? It’s a piece of fabric that is typically decorated, usually with band logos, and hangs from either belt loops or hooks on the back side of pants. They are another way to express yourself, and your favorites, through fashion. Gwen Stefani typically wears these on stage during concerts.
These are also very popular in the punk scene.
I made this for a No Doubt concert back in 2009 and then wore it again in 2012 to see No Doubt on Good Morning America and Jimmy Fallon.