Two men are facing each other alone in a large room. There is a clock on the wall. One man, who thinks of himself as a prophet, says to the other, “In five minutes you’ll be stabbed in the back.”

The other man is very distraught and stares at the clock. After five minutes he is stabbed in the back.

What happened?

If a mountain climber climbed up a mountain one day from midnight to midnight the next day and does the same thing the following day when coming down the mountain, would there be a time at which he was at the same position on the mountain both day?

A pet shop owner had a parrot with a sign on its cage that said “Parrot repeats everything it hears.” A young man bought the parrot and for two weeks he spoke to it but it didn’t say a word. He tried to return the parrot but the shopkeeper said he never lied.

How can this be?