From what I have noticed is that a lot of friendships with mixed races crack and joke about the other race, not to be racist, but to be funny. Think of how many black comedians make white jokes, how many Hispanic comedians make black jokes, and so on.
In some cases yeah, I've seen different ethnicities joke. But I've seen people I used to go to school with be awfully racist and xenophobic- mostly towards specific ethnicities. They see the racist propaganda from right wing groups on Facebook and agree with it. If anything I think they're just morons that believe anything they see on Facebook, maybe they don't mean to be assholes, it just happens.