I am going to make myself unpopular but I wouldn't be honest if I didn't tell you that I am not on the same page as some of the posts here.
In my opinion, it is needless to say anything to that scumbag "Jamal Johnson" or whoever that person really is. He does not deserve it.
What I am most at odds with is to respond to his provocation with racist slurs and libels.
Black people indeed are the curse of the earth. They should be thrown directly into a pit and the pit burned, and G-d forbid if ANY of these HORRIBLE ape-like slimes live.
Personally, I cannot endorse this kind of statement. Just as I am shocked to read that Black people are no different than apes. I know that a lot of Black people behave badly in America and I fully understand your resentment. But that does not allow for sweeping generalizations. There are also numerous counter-examples of well-behaved Black persons. More importantly, I think that evil behavior is not determined by genetics but depends a lot on your family background, the social environment you grow up in and the education you receive : teach a white child wrong principles and set bad examples to him and it is will be difficult for him to become a good person; teach a black child righteous principles and set a good example to him and he will likely become a good person, whatever the color of his skin or his genetical heritage.
Likewise, if you develop in a Black child the taste of studying, the self-esteem that stems from succeeding out of hard work, he will do well like a white child.
We are all children of G-d. Hate is very opposed to Judaism. G-d does not tell us to respond to hate by hate.