A Wizard's Staff Has A Knob On The End
A Wizard's Staff Has A Knob On The End is a famous drinking song, first mentioned in Wyrd Sisters. Due to the song being built around double entendres, Nanny Ogg has taken a shine to it, and she will happily belt it out to the night sky along with the also less-than-wholesome Hedgehog Song.
A version of the song, performed by Dave Greenslade, is available on the CD Terry Pratchett's From the Discworld.