1.)The smelly brown knuckle of the finger or thumb inserted in someones butt. 2.)The person inserting said finger or thumb 3.) The act of inserting said finger or thumb in one's butt, possibly due to boredom or lack of interest. 4.)Someone who complains alot but does nothing and/or offers no suggestions about how to remedy the problem he/she is complaining about.

Dave is such a butt-knuckle that rather than do something useful he'll just sit there with his thumb up his butt complaining about everything. Hey can you help me with this right after you go wash the stink off of your butt-knuckle. Don't go butt-knuckle on us now we may still need your help before it's all over.

Butt-knuckle by Bradley Brandt November 3, 2005

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Butt Knuckle

When a male wears his pants/shorts extra tight and his balls are showing. The opposite of Camel Toe.

Check out the Butt Knuckle on that guy!!!

Butt Knuckle by Skinnywalker January 13, 2005

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Popping your butt knuckle

Farting or getting raped in the ass by a large shemale.

Dude that one website you sent me to last night was digusting, I didn't know shemales could be Popping your butt knuckle.

Popping your butt knuckle by UF Omega September 13, 2011

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bustin' butt knuckles

The consensual act of having aggressive anal sex with someone who has horrific hemorrhoids in order to break them down

Angie knew when she had got hemorrhoids again it was time for Peter to start bustin' butt knuckles to get some relief

bustin' butt knuckles by von groovy April 11, 2019

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