I doubt whether racist taunts are unheard of in the six nations, Ab, though they pass unheard outside the intimacy of the front row of the scrum, where many things are said.
At a very junior level I remember getting an earful of (wholly inaccurate) anti-Semitic abuse from my opposing prop, who must have been confused by my black hair and beard. He was fresh out of school, one with a significant Jewish intake as it happens, and I had a quiet word with his captain in the bar after we had thoroughly beaten them.