Double Decoding Fun — Cynthia MacGregor

Maybe this book should be called TRIPLE decoding fun. It offers kids three kinds of fun to have: First in decoding the tongue-twisters and knock-knock jokes that are printed here in a letter-substitution code, then in enjoying the knock-knock jokes with friends and trying out the tongue-twisters on your own or with friends. (Decoded versions are in the back of the book, just in case you get stumped.)