As we grow up we have a variety of books to read for both young and old but when we were children or older which children's books do you find the most funniest? Mine would be Captain Underpants. That's one book series that had me laughing my head off over. The drawings and writing alone is creative,charming and downright hilarious to boot! There's also a series adaptation of the board game Clue as well. That too has some pretty funny moments.