AssFault

ButtCrack:
Because it’s literally a fault in your ass. Like the San Andreas Fault is a big crack in the ground.

There’s some rumblings coming from your assfault.

HTBP

"Here There Be Pee"
A tongue-in-cheek cartographic marking to indicate where the explorers stopped to relieve themselves. Parody of the classic marking "Here The Be Dragons."

Harrow, in consulting the map, saw that Sterling had marked the spot twenty yards from where they had eaten lunch, “HTBP”