trench booty

is a guy or girl that has a very long butt like the trenches in world war 1

Sha'Mel: hey Jon do you see that girl over there with that trench booty?

Jon: Hell yea i do that ass is long.

Booty Trench

When your ass crack is so deep and long and dirty brown and shit like the trenches from WW1

Hey man did you hear Lataetae has a Booty Trench?