The most obnoxious thing I see now is 20 year-olds lecturing an elderly American about any of this stuff. This is a function of how they've been raised, not taught humility, not taught that their views are not particularly important because they have zero life experiences. I know how embarrassed I am of things I said and believed at twenty, when I really didn't know anything.
I'd also like to know how you can be a multiculturalist if you don't know anything about the foreign cultures you attempt to venerate, nevermind your own. If you ever want to stump or silence them, ask them to tell you something about the history, the religions, the social structures of these places they claim to love. They know nothing about them. If they had a class allegedly based upon study of these cultures, it was undoubtedly fixated upon their oppressed/oppressor, one-size-fits-all explanation for everything. They were taught political ideology, not history or culture.