Unfortunately significant portion of my friends seem to think that saying racist, sexist, fascist things and laughing is funny and quantifies as a joke. Basically how do you get shithead white suburb kids to care about struggles of people and not play that off as a joke?
"I don't get it." followed by a "what's funny about that?" If they even try to explain it.
Depending on the kind of person, getting them to admit that they're punching down should make them cut it out. Hopefully they're that kind of person.