I am almost 72 and I have worn a sheet with eyes cut out as a Halloween costume in the mid ‘70’s after I got back from the war. I remember that one of the girls who had curly blond hair covered her face with black shoe polish and wore a cheap black hair wig at the same party. This was in suburban Baltimore and about all those at the party were white collar bankers. It was all in good, drunken, fun. Race relations were much better back then. Memories of the late ‘60’s riots were still fresh and the Negros just wanted to get along and live in relative peace.
I'm that much younger; no, I've never done such a thing, although I am a bit sick of the blackface whining. Big deal. Authenticity was the goal, not so much "making fun" as all these wussies try to fain.
The KKK thing is a bit worse, but still, it's just a costume, and not necessarily a "condoning" point.
Again, re: blackface, I say:
