its because somewhere out there...someone sat down and decided "hey im going to make a video of roosters, to the ill beats of this sweet sweet rap song. that song will be about how a woman shakes her ass thus enticing a sexual response (i.e. erection) out of me."
so somewhere out there, someone is telling us through music that roosters do it for them, and that is very giggle worthy at the least. i bet they have a hard time walking into paula dean's kitchen.