Although it's insulting ... it's just a part of being a minority in a country fueled on stereotypes. I'd just let it go and cool off. Work is work, nothing more. No need to prove a point to someone who doesn't have the capacity to accept things beyond his predetermined bullshit.

If it happens again, correct him. Plainly state, "I'm serious, I'm not laughing".



Not to side track, but this is exactly the reason why you see groups of people (of the same race) cling together as friends. The understanding of a culture is a very strong bond.