A black man who eats tons of hamburgers a per day and is super obese like a typical white American. A typical job of a black cracka is moderating discord because of his weight.
Mike is a black cracka. He sits on his laptop and moderates discord while eating hamburgers.
Black Crack is slang for vinyl in the DJ culture. It's called black crack because often DJs spend all their money buying vinyl (which is black, and the media which most proffesional DJs use). Since they buy it all the time its an addiction like crack, thus getting the name Black Crack.