fat flaps Share definition Flag A fat person's "boobs" which are actually just a piece of skin filled with fat. Fat person: Hahahah you have no boobs! Skinny person: Neither do you! You have fat flaps! fat flaps by Liissiieee (: June 22, 2011 0 0 Get merch Get the fat flaps mug. Buy Now — $32.95 See more merch