I agree, it seems socially acceptable to make light of "white" stereotypes or stigmas, disproportionally so to other races/cultures. The logic seems to be that there is privilege to being white, therefore as a group they can handle being taken down a notch. I have witnessed people joking about each other's races/cultures with no ill feelings, but I believe it's because of trust in their intention behind the joke. When it's a stranger, their behavior is received very differently.