Ask YC: Why does 800-GOOG-411 have a listing for "prostitutes" in SF?

If you call 800-GOOG411 in San Francisco at least, and ask it for a "prostitute", it has an entry and responds, offering up a choice of hotels. What tech powers GOOG-411 that allows for something like this (it certainly doesn't respond to other nonsensical queries) - or did I just discover an easter egg?