Very similar circumstance happened to my son in a bar in Chicago. Standing with his girlfriend when a black thug all of the sudden started threatening him. They had had no interaction whatsoever. This is all horrifying and scary as hell.
He was trying to start an argument to justify punching or beating you. Black “youths” do this all the time. I’ve had it happen to me, years before anyone heard of Trayvon Martin. You ignore the taunts, if possible.