““For the professional pickpocket, one of the best tools he could invest in is a wall-mounted sign that reads “Beware of Pickpockets.” With this unlikely device, he needs simply to hang this sign on the wall of a railway or bus station and then sit back and observe as legions of well-meaning people casually pat their pockets or purses, reassuring themselves that their valuables are where they should be, all the while giving the thief clear instructions on where to find the goods.””
