Putting a racial slur on a cup of coffee you're selling to a custome—after being given his proper name, no less—is completely inappropriate and wrong. It's also totally unprofessional and should never occur, because it damages the company's brand and image.
Once identified, the offending employee should be immediately terminated, or perhaps have his pay reduced and then undergo training which educates hm/herr as to why racial slurs are unacceptable, and bad for business...
I repeat, 330 million. Heck, some of them even shoot up schools.