An old timer was sitting on his porch when a young man walked up holing a pen and clipboard.
"What are you selling, son?" asked the old man.
"I'm not selling anything.  I'm the census taker."
"The what?"
"The census taker.  We're trying to find out how many people there are in the United States."
"You're wasting your time with me," said the old man.  "I have no idea."

Hey!  They don't always have to be dirty.