Horses ass Share definition Flag An offensive name that can only be used if a person slaps you while you have a sunburn. Made famous on family guy when stewie says it. Peter: Hey stewie! (slaps on butt) Stewie: Ahh you horses ass! Horses ass by Raptapwnage August 20, 2010 0 0 Get merch Get the Horses ass mug. Buy Now — $32.95 See more merch