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1.
A fart that's too greasy to be called wet.
I heard Dave fart, I didn't believe that it was a real fart. It sounded like what you get when you put butter in a whoopee cushion. It was a butter fart.
by A member of the Team Cripple January 22, 2008
 
2.
A butter-fart is the act of slathering butter inside of your anus, and releasing a burst of pressurized gas from your intestines. The butterfart originated on a fateful ski trip to canada.
Lupe slathered his ass with butter and proceeded to "Butterfart" on don's face.
by Hank pruyn January 17, 2012