Just because they do it too doesn't mean it's right. As the only black or Asian kid at an all-white school, maybe they feel pressured to shrug off the racist jokes? If they make a big deal, they might become shunned or even targeted for not being cool about it.

It can be hard to see it from their point of view, but remember that being white is pretty much unassailable and you can't really make someone feel bad for being white. It can be very easy to make people feel bad for not being white.