A joke by any other name

At first I started to write "Wow, Mallard actually made me laugh." Then I started thinking about the joke. I've read that some of the elements of humor are familiarity coupled with an unexpected turn. That is, a joke about an obscure 19th century supreme court judge generally won't work with most audiences, as there is no common background. So why does Mallard's joke "work?"

Simple: We expect him to be a racist. He's demonstrated disdain for just about every group that isn't White, Christian, and ultra-conservative. So we read this strip, and think "Wow, he's really about to pull a Mel Gibson here," only to have the punchline deviate us from our expected destination. Hence, humor. But would this joke work in Doonesbury? For Better or For Worse? Or, for that matter, just about any other comic strip? I don't think so. We laugh because we wouldn't be surprised if Bruce Tinsley started up on Jews.

Not really an enviable position, is it?