Flat Garrett's Travels

Flat Stanley is a really cute children’s book and it has taken off into the Flat Stanley project where every year school kids send out a Flat of themself and see how many places it can go.

Here’s the synopsis courtesy of Wikipedia:

Stanley Lambchop and his younger brother Arthur are given a big bulletin board by their Dad for putting pictures and posters on. He hangs it on the wall over Stanley’s bed, but 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. Stanley even helps catch some art museum sneak thieves by posing as a painting on the wall. But one special advantage is that Flat Stanley can now visit his friends by being mailed in an envelope. Eventually Arthur, who tires of all the attention Stanley has been getting, reverts Stanley to his proper shape through an air pump used for footballs.