If it looks like a duck, walks like a duck, and quacks like a duck...
Not to be insensitive or crude or anything, but isn't there the slightest chance that some of this might possibly be related to the obsession with the derriere within rap/hip-hop culture? I mean, from "Baby Got Back" years ago, to these soft-porn videos like "Right Thurr" that prominently feature booty-shaking and more booty-shaking...is there not, perhaps, an unhealthy fetish with the posterior as a sexual object rather than as a waste-disposal site?