unbelivafat Share definition Flag The state of being unbelievably fat. Too big to be pleasantly plump. 1.The dog was so unbelivafat it couldn't fit through the door. 2.In a sentence: He is so unbelivafat. unbelivafat by Bob1 November 9, 2007 0 0 Get merch Get the unbelivafat mug. Buy Now — $32.95 See more merch