A rich man in the Qi Kingdom had two silly sons, but the rich man loved his sons very much and they were the apples of his eye. 

One day, a man named Ai Zi said to the rich man, "Your sons are so stupid and know nothing about the world. How can they take your property over after your death?"

Hearing these words, the rich man became a little bit angry. The father said, "Everyone says my sons are very smart and praises them for their good virtue. What you say is sheer nonsense（一派胡言）!"

"Then let's test them. Ok?" Ai Zi suggested. The rich man agreed.

The father called his two sons before Ai Zi, who asked the question, "Do you know where rice comes from?"

The elder son smiled and answered, "Anyone with sense knows the answer, that rice comes from the kitchen."

The younger son blinked and said, "You're wrong! How can you say rice comes from the kitchen! It indeed comes from the bag."

The rich man looked at his sons and turned red with anger. "You both are so silly! Why don't you ask me when you don't know the right answer? You are both wrong! Rice comes neither from the kitchen nor from the bag, it comes from the barn!"

The moral of the story is that one may do foolish things when he pretends to know the things he is actually ignorant of.