A combination of the words "fart" and "butt", showing immaturity through a lack of a better insult.
"Go buttfart out your fartbutt, butt farter!"
by Gareth J May 18, 2007
Fartbutter is a fart let out with a little wetness that stays in between the buttcheeks. It makes your buttcheeks slipper, so they slide back and forth as you walk or even run. So as the old saying goes "slippery when wet"
Damn, my ass has enough fartbutter build up in it.

Geesh, when will I let a fart with out the butter?
by fartyuyiorieoirtjo September 16, 2010
Funni discord user whos name is fartbutt. Cause why not
Fartbutt
by Real_Fartbutt August 30, 2021