FAT-ASS Share definition Flag To be huge or bigger than anything in this world. Enormous beyond all extent. gigantichugekong 1) She got hit by a Fat-Ass truck! 2) That byotch left a Fat-Ass mark on his face. FAT-ASS by LEE The Dope Form March 31, 2009 0 0 Get merch Get the FAT-ASS mug. Buy Now — $32.95 See more merch