A person so dumb they can't tell the diffrence of a penis or finger and think the knuckle on a finger is the end of the dick head.
That bitch was so gross I couldn't get hard. So I fucked her with my finger and told her I have a small dick. She said the end of my head was big she is so dumb what a fuck knuckle
by Rawdog75 January 13, 2025

Dude this chauch was talking serious trash at the club last night, so I straight up Knuckle Fucked his ass.
by Freak Sho September 26, 2010

When hitting a large jump (booter) mainly on skis there is a roller or knuckle that the jump sits on. If you hit that jump and land a little short that is called a case. But if you case the jump so hard that you are ejected from your skis and you thrust your body so hard against the landing that is called a Knuckle Fuck because you are fucking the knuckle.
by AbsorbedSpoon3 July 5, 2019

by Wayne Schlinger & Kevski September 23, 2021

by elcapitandeganja October 18, 2013

A large, ignorant and lazy individual with poor hygiene. Smells like they haven’t wiped their ass since the 8th grade.
by Jack Mahaugov September 16, 2022

by Marty's ass September 25, 2020
