The king wanted to go fishing. 

He called on the royal weather forecaster and inquired as to the weather forecast for the next few hours. The weatherman assured him there was no chance of rain in the coming days. So the king went fishing with the queen. 

On the way, he met a farmer on his donkey. Upon seeing the king the farmer said, “Your Majesty, you should return to the palace! In just a short time I expect a huge amount of rain to fall in this area."

The king replied, “I hold the palace meteorologist in high regard. He is an extensively educated and experienced professional. And I pay him very high wages. He gave me a very different forecast. I trust him.” 

So the king continued on his way. However, a short time later, a torrential rain fell from the sky. The king and queen were totally soaked, and their entourage chuckled upon seeing them in such a shameful condition. 

Furious, the king returned to the palace and gave the order to behead the professional. Then he summoned the farmer and offered him the prestigious and high paying role of royal forecaster. 

The farmer said, “Your Majesty, I do not know anything about forecasting. I obtain my information from my donkey. If I see my donkey’s ears drooping, it means with certainty that it will rain.”

So the king hired the donkey, and thus began the practice of hiring dumb asses to work in government and occupy its most influential positions. The custom is unbroken to this day.