This term is very similar to the term "How's it hangin' " The only real difference being that how's it bangin' is less formal than it's counterpart. The "It" in question is very contextual to the situation and could really mean anything.
I was bangin' 7 gram rocks, That's how I roll. Winning
I have one gear: GO - epic winning
Are you bipolar?
I'm bi-winning
Win here, win there, win, win everywhere, where