The boy who cried wolf by Aesop

There was a Shepherd Boy who tended his sheep in a mountain. The boy was bored resting on a tree when he had an idea.

He went near the village calling out "Wolf, Wolf," and the villagers came out to meet him and the boy laughed.

A few days after he did the same and again the villagers came to his help again. After this a Wolf actually came out from the forest. The boy cried out "Wolf, Wolf," still louder than before. But this time the villagers thought the boy was lying again,

and nobody came to his aid. So the Wolf ate the boy's sheep. Moral: A liar will not be believed, even when telling the truth.