Why do black men only have nightmares? Because the last one who had a dream got shot!
Are you mocking black people?
No, it's just a joke. I don't mean to offend anyone.
Well it's not funny to joke about MLK being assassinated. It was a tragic event in history and you should be careful about making racist jokes like this.
Oh, I'm sorry. It was not my intention to offend anyone.
It's good that you understand that these types of jokes are not good. Saying that all black people who dream about bettering things end up dead is not well-thought out humor. Pick a better subject to use to make people laugh.