it's a jaw breaking maneuver in which the victim's mouth is opened and placed in a "biting" postion on a street curb then the assailant gives a hard stomp to the back of the victim's head. causing the victim to suffer broken teeth, jaw or somecase's even death.
Paco-"did you hear the Juarez boys gave Joey a mexican snake bite."
Dave-"why'd they do that?"
Paco-"cuz Joey was talking too much with La Eme."