anal emergency

That feeling you get when you have to go. Right now. Or you may shit yourself.

Sorry I knocked you over grandma, I had an anal emergency!

Emergency anal evacuation

An intense need to vacate your bowls. IE shit.
Is usually accompanied with stomach aches.

Usually but not exclusively involves explosive diarrhea.

Dan: Dude where were you earlier?

Steve: i had some bad sushi and had to execute and emergency anal evacuation.