This book gets me just about rolling with laughter, and despite a bit of potty humor, I've even worked with it in a fourth grade classroom with great success. It's an awesome fun way to introduce idioms, and it can be a great srpingboard to have kids tell a story about a misunderstood idiom. Prepare for some silliness, but loads of learning and enjoyment.
This one may only be for the young and young at heart, but it's become a favorite of mine! I really enjoy all of Lane Smith's wonderfully, childishly, funny books.