The Flat Stanley book series by Jeff Brown is so much fun to read. This is what the Flat Stanley books are about: Stanley Lambchop and his younger brother Arthur are given a big bulletin board by their father to display pictures and posters. He hangs it on the wall over Stanley's bed. During the night the board falls from the wall, flattening Stanley in his sleep. He survives and makes the best of his altered state, and soon he is entering locked rooms by sliding under the door, and playing with his younger brother by being used as a kite. One special advantage is that Flat Stanley can now visit his friends by being mailed in an envelope. Stanley even helps catch some art museum thieves by posing as a painting on the wall. Eventually Arthur changes Stanley back to his proper shape with a bicycle pump. (http://en.wikipedia.org/wiki/Flat_Stanley).