This is hysterical

Never laughed in my life like this
@Sataninc: Muted
To answer your question:
The joke is not racist because the black man is throwing the white man in sake of his past actions, therefore white people like me at some certain point can understand a bit of racist meaning behind it. But if we are speaking from retrospective is the same as some people will point at hitler and the germans for their great grandfather's death.
I can't come to a better solution to this =)