I think the best thing to do is to ignore them. If they catch you on video saying the N word to them, and place it online, it could cause you problems at your job or future jobs. Also they really aren't worth speaking to. I would consider them animals in the same way that dogs bark and growl as you pass by. Those "Black Hebros" are so far below most of humanity that they just don't merit a response at all. I don't fault people who do insult them to their faces, because it can be fun to do that, but honestly it's like yelling at a barking dog.