I wouldn't ignore someone who yells to get my attention in public. Yes, in the right circumstance I will respond to nigger, and my response will not be thought out and dangerous. In the situation described, there is no need for immediate action. "who the fuck are you talking to?"- followed by ignorance, then "Motherfucker, I know you are not talking to me!" as loud as possible, then turn around and see how ignorant a motherfucker is, or do I have to turn my ass around again. No buttons, but if you really want the horns...