I'm going to cheat.
A Child's Garden of Verses by Robert Louis Stevenson because they were my very bestest favorites when I was tiny.
The Phantom Tollbooth by Norman Juster because the riddles and twists of absurdity are great every time - in context and out.
And...
Flashman by George Macdonald Fraser for the adult version of absurd humor in a story with riddles and plot twists and plenty of fun.
What do you think?