How about this:
There was a man living in a farm with his extremely stupid son. One day, when a visitor is about to come, the man told his son, "When he comes in, he'll ask where I am, tell him 'he is in his office.' When he goes further, he'll see a stump. Tell him that the tree was cut off. When he tells you that you are really smart, say it's a family trait."
When the man comes and the boy goes to greet him. The man asks, "Say, there were pigs in this area, where are they?"
"They're in his office," the son replied.
The man walks further in, and then asks him where his father was.
"He was chopped off," was the reply.
"You are a really stupid boy," says the man.
"It's a family trait," replied the boy.