That one

This could be the slip of the tongue that goes down in history. I'd heard about it before I saw it, and even then I was stunned. He really did say it.

I say "slip of the tongue" not to suggest he didn't mean it. I use it in the Freudian sense: he did mean it, he just didn't mean to say it out loud.

It would have been catastrophic against a white opponent. Now, he may as well start calling Obama "boy".