knuckle beefing Share definition Flag To violently finger fuck a girl or to ultimately become knuckle deep in her vagina while furiously finger fucking. Dude! I was knuckle beefing that girl from the party last night so hard. knuckle beefing by blowjobjack December 28, 2019 0 0 Get merch Get the knuckle beefing mug. Buy Now — $32.95 See more merch