This honestly must be an american thing. The only time I ever remember any of my friends or family saying it was when my uncle told my cousin he was going to play "n-word ball". My cousin was really embarrassed and called his dad out for it right away. And that was in the early 90s....
I can;t imagine any of my white friends saying it. Maybe when they were under 21.... I'm seriously surprised so many Americans feel this is normal behaviour. I guess it just goes to show how much worse blacks are treated in USA than Canada.