During the act of anal intercourse, the person on the receiving end has a nasty case of firerreah.
The outcome is something to the effect of putting your thumb over a garden hose.
Dude, last night a brownie earthquake went down in my house and it shot about 3 yards in each direction.
Poop Terminology: a poop that is watery, brown, and stings. The after effect is mild to severe itching.
When John finished in the bathroom, he knew he had made a brownie earthquake because his butt was stinging.