The muscle in the butt used as in insult towards someone acting dumb.
Person1:Hey wanna get some beer?
Person2:You're old enough to drink?!
Person1:I'm23 ass muscle.
by what's_a_pseudonym? January 12, 2010
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Somebody whose incapable of building muscle.
A cunt that's trashing everybody online and is a skinny piece of shit.
by Roided Beast March 16, 2018
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