When a person has a violent and severely explosivebowel movement so much so that it resembles a digestive "exorcism" of foul smelling, rotting waste matter sent by Satan through the depths of your cursed colon. Like the "asspocalypse" this kind of bowel movement can trigger loss of consciousness, muscular spasms within the legs and may need supervision by the occasional priest.
"Dude, did you hear Calves in the 4th bathroom...it smelled awful...I walked right into her demonic colonic."
A duck that somewaht resembles a demon, has strange powers that make it a very good distraction. Appears multiple times in the web-comic El Goonish Shive.