A fork of Rural Dictionary
A "Rectum Apocalypse" occurs when Satan emerges from ones anus to destroy the world. You can also describe an extroardinarily large dump as a rectum apocalypse, or an anal armageddon.
Teacher: "Billy, I told you that you had 3 minutes in the bathroom! You're 30 minutes late!" Billy: "Sorry, Teach! I had the rectum apocalypse!"