Butt Heaving 

Agressive diarrhea, more violent in nature than regular diarrhea, and where each episode requires a longer than normal visit to the restroom. Similar in nature to extreme vomiting after drinking WAY too much alcohol after a long night of partying except that material is ejected from the other end. (The word is funnier if pronounced "Buttheavin' ".)

Dude, why were you in there so long?
Sorry, I was butt heaving.

Don't go in there yet, someone was just in there buttheavin'.

Butt Heaving by Internet Dan February 8, 2010

buttheading 

a bit like headbutting but instead it is the act of randomly running behind an angry mob and using your head to ram their asses.

lets go buttheading into that angry mob of bearded bald men

buttheading by mike blown January 17, 2008