Those goofy squares of cloth, sometimes cut from an old tshirt or some other random piece of cloth (but now available at hot topic probably) that alot of street punks wear dangling from the back of their pants.
Synonyms for buttflap
On this page, you will find 30 slang terms related to buttflap. Some of the top words include: spookypants, foofie pants, spants, fast, chino chumps, and 25 more.