100 fat ass Share definition Flag Used when a person does not want to tell their real weight but also knowing they are fat. person 1 "so how much do you weigh" person 2 "100 fat ass" 100 fat ass by imthatredheadbitch March 29, 2010 0 0 Get merch Get the 100 fat ass mug. Buy Now — $32.95 See more merch