nuck is kinda what a horse does when it's mad. so when a human nucks, then they kinda of do a crazy body movement such as kicking, jumping, jabbing, nodding the head vigorously, etc....
buck is kind of a short way of saying buck wild
or getting crunk
so basically, it means to get crunk and go crazy if you're a wild type of person. This is mostly done when listening to rap music, dancing in the club, or getting into a fight.