The act of a woman or man of a different race having sex with a black male for the first time. This is frequently used with the phrase "once you go black, you don't go back."
I'll be blacking his wife while he's away on the business tripnext week.
Claiming that a character of ambiguous or null race is black, usually stating that people who think otherwise are racists or white supremacists (which is not usually the case at all).
Man 1: So, I finally asked her out and she said 'yes'.
Man 2: Are you blacking me, she's way out of your league!
Man 1: Naw, man. I would never black you.