in jail now you cant get them im told ; monopoly games that is

By Brian McMahon
(Mental Floss) -- Park Place, Boardwalk, and a hidden map with a secret escape route? For Allied POWs during World War II, Monopoly® games came equipped with real-life "get out of jail free" cards.
During World War II, the British secret service hatched a master plan to smuggle escape gear to captured Allied soldiers inside Germany. Their secret weapon? Monopoly boxes.
The original notion was simple enough: Find a way to sneak useful items into prison camps in an unassuming form. But the idea to use Monopoly came from a series of happy coincidences, all of which started with maps.
http://www.cnn.com/2007/LIVING/wayoflife/12/05/mf.waropoly/index.html