Puzzle of the Five Pigs
History behind it, according to psywarrior.com:
For many years prior to WWII various venders made and sold puzzles to children. These puzzles had a number of different pictures on the front, and when folded in a special complex way depicted a hidden picture of an old man, or sometimes a political laeder, sports figure or movie star.
During WWII the British Special Operations executive is believed to have produced a number of different puzzles showing four pigs on the front, that when folded depicted the face of Adolf Hitler. At least four types of the pig puzzle are known, and it is believed that besides being used in Allied countries as a morale booster, they were also shipped to partisans in Nazi-occupied nations to attack and belittle the German Fuhrer.
One type with English text says, "Fold as directed to find the biggest pig of all." Another English-language puzzle says, "Puzzle of the pig. Here is the puzzle of the fifth pig. To find a fifth one fold as directed." A third puzzle is found in both French and English and was also distributed in Australia.
Apparently, many of these puzzles were also dropped by the Royal Air Force. In 2008, I received a letter that stated:
My father came to Canada from the Netherlands in the 1950s. When he was a young man in Holland during the war he collected different things. He has a paper he said they threw out of an airplane. It is written in Dutch and English. "Can you find the 5th pig." There are four pigs on the picture, and when folded right the four pigs together make a face that resembles Hitler.
Some more people mentioning inheriting one of these from a grandparent.
If anyone has anymore information on the background and history of this and related, let me know.