Taxi drivers, waiters, salesmen, etc. "accidentally" drop your delivery and raise the amount as it looks the same. But it is a substitute for coins and banknotes to less dignity ones.
A cashier counts your change slowly and often pauses in the hope that you'll lose patience and either leave, or relieved at last “keep the delivery" that you counted far less than needed to spend your time waiting.
Someone comes up to you and offers to buy the map. It's unfolded in front of your face to showmanship, but it's just a distraction, while other person is stealing out of your pockets.