Knuckle-Beef Share definition Flag A) To fist an asshole. (verb) B) something that is unpleasant (noun) "Dude I gave her some serious knuckle-beef last night""Man, that test was some major Knuckle-Beef" Knuckle-Beef by Jomofo September 27, 2012 0 0 Get merch Get the Knuckle-Beef mug. Buy Now — $32.95 See more merch