The old informative Persian story.
Once upon a time there was shepherd who use to take his sheep to the hill near to the village he live. The shepherd always enjoyed to cracking a jock with villagers and amuse himself a little; thus when he reached the hill shouted: "wolf..wolf". Then, the villagers ran with cudgel to rescue a shepherd and sheep, but they found no wolf there and saw him laughing; he repeated his joke for many days and laugh at the villagers when they came.
One day in the evening when he was on the hill with his sheep; suddenly, the wolf had truly come at last and jumped upon the sheep. He was shouted "wolf...wolf..." but nobody believed him payed any heed to his crying and wolf killed all sheep and shepherd could do anything.
The moral of the story: There is no believing a liar, even when he speaks a truth.
Useful words and definitions:
Hill: A natural elevation of the earth's surface, smaller than a mountain.
Near: Close; to a point or place not far away, or to a short distance.
Village: A small community or group of houses in a rural area, larger than a hamlet and usually smaller than a town.
Amuse: To hold the attention of (somone) pleasantly.
Numerous: Very many; being or existing in great quantity. [noo-mer-uh's, nyoo-]
Wolf: Any of several large carnivorous mammals of the genus of the dog family.
Carnivorous: Eating animal flesh. [kahr-niv-er-uh's]
Mammal: An animal having the body more or less covered with hair.