I didn't get last Friday's XKCD until I read this post from someone who'd been in the same boat, who found out what it was: a Discovery Channel commercial that is 31 flavors of awesome. watchy watchy.
Apparently there are already people making other riffs on it. Note that since I have now discovered this meme, it must be at least half over, but I will be enjoying it for a while because I like the song so much. Another interesting bit of information from that forum thread was that the tune is from a children's song called "I Like the Flowers."
I have a strong suspicion that baby will become quite familiar with this tune in some version or another.