I was thinking of Witches Abroad today and had a big grin on my face. Specifically the sequence when Greebo became human, then goes about seducing the available ladies in polite society with his animal magnetism. It was a hilariously written sequence and actually one of my favourite Pratchett books. The Sphinx's riddle from Pyramids and Death protesting that he didn't kill Elvis in Good Omens (actually all of Good Omens is genius! - I never stop being upset at the thought of Terry Gilliam directing the sequence with the marketing people playing paintball).
Pratchett writes to a formula and that can annoy through sheer repetition, but he can produce this nuggets of comedy gold.