One out of five grocery stores in Prague cheated customers buying snacks, often by more than half the value of the purchase. This is according to a new study called “Cheating Customers in Grocery Stores: A Field Study on Dishonesty,” published in the Journal of Behavioral and Experimental Economics. The researchers examined 259 grocery stores in Prague, with the help of customers posing as foreigners unfamiliar with Czech currency. They gave clerks a chance to steal money by not giving back the correct amount of change.