Keep in mind, like I said in my post, that Blacks live in a world institutional racism is rampant. It’s not so much that they are reacting to you personally, but to a manner they/we have been treated throughout their entire lives. In addition to having your black friend present, another thing that disarms people (of any race) in those situations is your response. A hot-tempered and defensive “no, I’m not!” only gives the customer more justification for their actions. A cool, calm, and collected response coupled with a little empathy will go a long way. You don’t have to say, “ … I know why you might think that I’m a racist because of my race, but I am not. I’m only doing my job,” but to respond with that intent will work wonders. I know of what I speak. Trust me on that one.