poo-imperative 

The undeniable need to take a dump that happens after one has held it back for as long as one can. The state of mind when one's bowels decree that they must be evacuated immediately.

self -"I really don't want to use a gas station bathroom..."
ass -"poo-imperative!!"
self -"dag yo"

poo-imperative by AKAStavros November 6, 2009