Travelling on a plane was a man who was proud of his intelligence. When he discovered that the person sitting next to him was a worker, he suggested they think up some riddles to pass the time.
"If you can’t answer mine, you must give me $5," he said. "And if i can’t answer yours, I’ll give you $5, OK?" "NO!" answered the worker, "I’m tired and i want to sleep"
"Well a better idea" said the man intensively, "If you can’t answer mine, you must give me $5 and if i can’t answer yours, I’ll give you $10,"
"Alright" the worker said after a little thinking, "And i will go first". The man agreed.
The worker then asked: “What has six feet on the land and only three feet when swimming?" then continued "I sleep, when you find the answer wake me up!"
"OK" the man said. He thought for very long time about this, but reluctantly he had to concede defeat.
When they reached their destination he woke the worker up and said "here's your $10; what’s the answer?"
"I don't know", said the worker; "here's your $5."