Knuckle Fucked Share definition Flag It is when you clock a muther fucker in the face while you have your middle finger extended. Dude this chauch was talking serious trash at the club last night, so I straight up Knuckle Fucked his ass. Knuckle Fucked by Freak Sho September 26, 2010 0 0 Get merch Get the Knuckle Fucked mug. Buy Now — $32.95 See more merch