Remember that nonsensical "God Equation" that was ripped apart over at Pharyngula about a month ago? Yeah, I don't think its creators will get this joke:I really think the amount you laugh* at xkcd could be a good predictor of nerdiness/science knowledge. I know when I stare at a comic scratching my head, it's because I don't know something. This frequently happens when the punchline has to do with programming. Sadness.
*Assuming laughter correlates with getting the joke. If you get it but don't laugh, I don't get your sense of humor. If you don't get it but laugh, you may be insane, really like stick figures, or have a judgmental nerd peering over your shoulder.