An old man was sitting on his porch （门廊）, when a young man walked up with a pad and pencil in his hand. 

"What are you selling young man," the old
man asked.

"I'm not selling anything," the young man said. I'm the Census Taker(户口调查人员）."

"A what?" the old man asked.

"A Census Taker. We are trying to find out how many people are in the United States."

"Well," the old man answered, "you're wasting your time with me, I have no idea."