Is there a popular saying that says it's been done by black(meaning it's a dumb or lazy thing)?
Not popular, by any means, except among morons, but some people say, "That's a [N-word] thing to do," or "That's so [N-word]" One reason, among several, that it's not popular is that if you get caught saying it, the consequences may be serious. That's true among black people, too. I have many well-educated and successful black neighbors. They wouldn't tolerate that from their children.