Knuckle Sacker Share definition Flag Someone who will have sex with anyone. Damn, look at that girl he's with... He's a total Knuckle Sacker!!! She's hideous! Knuckle Sacker by boinkacceptor September 26, 2010 0 0 Get merch Get the Knuckle Sacker mug. Buy Now — $32.95 See more merch