Dan was the doorman of a club in a big city. Everyday, thousands of people passed his door, and a lot of them stopped and asked him, "What's the time, please?"
After a few months, Dan said to himself, "I'm not going to answer all those stupid people any more. I'm going to buy a big clock and put it upon the wall here." Then he did so.
“Now people aren't going to stop and ask me the time," he thought happily.
But after that, a lot of people stopped, looked at the clock and then asked Dan, "Is that clock right?”