The Unlocked Safe

A burglar, needing money to pay his income taxes, decided to rob the safe in a store. On the safe door he was very pleased to find a note reading: "Please don't use dynamite. The safe is not locked. Just turn the knob."

He did so. Instantly a heavy sandbag fell on him, the entire premises were floodlighted, and alarms started clanging. As the police carried him out on a stretcher, he was heard moaning: "My confidence in human nature has been rudely shaken."