look up any word, like darude - sandstorm:
 
1.
a stupid person or a hole
josh is a butt muscles
by ABITTY February 27, 2009
 
2.
Douche Bag.
White Hat.
Poser.
D. Metzler From Baltimore Maryland
"Butt Muscle Is The New Douche Bag."
by Windsah Clang August 21, 2009
 
3.
The name you give to a friend(or foe) , for being a dumbass.


DUDE!, i saw Matt talking to these hot chicks yesterday and he told me that he was busy, what a butt muscle!
by D-Peezy February 25, 2009