Through careful observation and years of study, one isolated case in North America has been proven. The "No Bum", is a severe disorder where a female's back starts at the shoulders and proceeds down until it splits into two components (legs). No pelvis has been found in this case. The gluteus maximus is missing. Sadly, those with No Bum will be unable to procreate with a black man. Women currently studied with Nobuminitis often resemble Buzz Lightyear.
Black 1: Yo, Nigga check out that chick.
Black 2: Buzz fuckin lightyear?
Black 1: Nah mane, that chick got No Bum!
Black 2: Daym..