.....

One day, an old man boarded a bus. As he was going up the steps, one of his shoes accidently slipped off. The door closed and the bus moved off so he was unable to retrieve his shoes.

Then the old man did something unusual. He calmly took off his other shoe and threw it out of his window. A young man on the bus saw what had happened and was extremely puzzled by the behaviour of this old man.

Finally, he could not contain his curiosity any longer. He approached the old man and asked him,
"Uncle, I noticed waht you did. Why did you throw your other shoe out as well?"
The old man promptly replied,
"So that whoever finds them will be able to use them."