Horizontal Butt Crack 

The horizontal crack formed between a womans butt and her upper leg. Usually, this crack is found in latino, or african women. A pseudo crack can be created when a woman is wearing pants that create the allusion of a HBC.

Jennifer Lopez, sumo wrestlers. Used in speech: "Dude, she has no boobs, but did you see her Horizontal Butt Crack"

Horizontal Butt Crack by riversabound October 20, 2010

Horizontal Buttcrack 

A totally regular and very common butt crack, like mine

Can you believe that there's people out there that have vertical butt cracks? Not normal completely common horizontal buttcracks like yours and mine.

Horizontal Buttcrack by nonvertical September 5, 2018