Re/Search: Pranks – entertaining, and often inspiring even if the examples don’t apply directly or are… let’s just say unethical.
Only Joking by Jimmy Carr – If there is a book on comedy theory (that you’d actually want to read) this might be it. Analysis of the history of comedy, different theories about what makes us laugh, and lots of jokes.
Sataristas by Paul Provenza and Dan Dion – First hand interviews with comedians of all kinds. Many valuable insights that, with a little creativity, you can apply to your practice.