Passing through London earlier this week, I visited a friend who had met Paul Robeson during one of the latter's trips to England several decades ago. Robeson told my friend of a reception at the White House, where he had been invited by First Lady Eleanor Roosevelt. As noted here, "At the height of his popularity, Robeson was a national symbol and a cultural leader in the war against fascism abroad and racism at home."
A certain US Senator approached Robeson and addressed him as "Professor." Robeson, confused, said, "Senator, I am not a professor. Why do you call me that?"
The reply, "Well, normally, I would call you nigger, but I can't use that term in this White House, so I'll just call you Professor."
Note: Picture courtesy of Wikipedia.