look up any word, like fleek:
 
1.
someone who does nothing. Sits around all day with their thumb up there ass to the knuckle.
Paul: Hey Todd, did you get that work done that you were supposed to do?

Todd: Aww, meant to, but didn't get around to it yet, sorry dude.

Paul: Yur a fuckin shit knuckle Todd, get to work!
by hecklndecalr March 19, 2010
 
2.
A bump protruding from a log of shit resembling a knuckle. Shit knuckle.
That dude is a real shit knuckle.
by Andrew X January 26, 2005