1 definition by DMazzIV

poop-knuckle

The second knuckle in (heading towards the hand). Originating from the knuckle at which you stop at when inserting a digit into another's asshole.
Used to warm up/stretch out an asshole before anal sex.

I was playing ping-pong and the ball hit off my poop-knuckle.

by DMazzIV August 23, 2006