look up any word, like ethered:

1 definition by purplecalculus

 
1.
When the muscles of the buttocks tighten up suddenly and unnecessarily, causing the feeling that the butt is under attack.
Often times this happens when you have to poop really bad.
John: Ah, butt attack!
Moses: You have to poop, man?
by purplecalculus June 26, 2011