I had a martial arts Sensei, who was neither white nor black. There were multiple black students in our class, with belt rankings as varied as the rest of us. One white belt student who happened to be black was chronically late, whined a lot, and had an entitled attitude in general. Sensei tore into this person with absolutely no mercy. Once I heard the student complain in class, "Why are you picking on me so much??" To which Sensei responded, "Your horrible attitude! 20 push-ups now!!"

I forget if this student shaped up, or stopped coming around.