Granny Weatherwax, Nanny Ogg and Magrat Garlick have hied themselves off to the far-off city of Genua for the Purposes of Narration. Once there, there are interesting problems regarding food and accomodation, but for reasons unclear, in one of the places offering the former, Granny decides she knows a joke and proceeds to tell it.

It's the Alligator Sandwich joke but she doesn't understand why it's funny - just that it is. Unsurprisingly, she therefore misremembers the punchline. :-) The correct punchline is "...and make it snappy!" just in case *you* don't remember it. (-:

Wade.