There was an old snake named Mandavishya, who lived near a mountain. 
 
Due to his old age, he was unable to prey on frogs. He thought, "I am too old to hunt for food. I will not be able to live long without food, and it is only going to make me weaker to hunt, as well. I have to think of something". 
 
Suddenly, an idea struck him. As planned, he went to a nearby pond, which was full of frogs, and relaxed on the bank of the pond without any intention to hunt. He behaved as though he had nothing to do with the frogs. 
 
At first the frogs ran away, but as he was not hunting, the frogs gathered some courage and approached him. One of them asked, "O Snake! Why do you not hunt, as is your behaviour?" 
 
The snake replied casually, "I have no desire for food, as I am unfortunate. I'll explain to you. Last night, when I was wandering about in search of frogs, I bit a Brahmin's son in frustration of not finding any prey. The Brahmin cursed me. He said, 'From now onwards, you shall be able to do nothing but serve frogs. You will have to live off what frogs offer to you!' And so, I lie here, to serve any frogs who wants my services. I can give a ride on my back to any frog who wishes for a ride" 
 
When the news reached the king of frogs, he visited the snake along with his ministers. On being assured by the snake that he means no harm, the king decided to take a ride on the snake's back. The snake rode him around the pond, and the king was very entertained. Even the ministers and other snakes took turns to ride the snake, and they were very entertained, too.