Buy a pig

A man from the city decided to buy himself a pig, so he took a drive in the country until he came across a sign reading, "Pigs for Sale." Turning into the drive, he parked next to an old farmer standing by a pen full of pigs
and explained his mission. Agreeing to a price of a dollar a pound, he picked out his pig, whereupon the old man picked up the pig by the tail with his teeth.

"Ayuh," he said, setting the squealing animal down, "that there pig weighs sixty-nine pounds."

Noting his customer's astonishment, the farmer explained that the ability to weigh pigs in this manner was a family trait passed down through the generations. Skeptical, and not wanting to be taken for a city slicker, the man insisted on a second opinion. So the old farmer called his son over from the barn, and the boy in the same fashion pronounced the pig's weight to be sixty-nine pounds.

Convinced, the man pulled out his wallet, but the farmer asked him to go to the farmhouse and pay his wife, who would give him a receipt. The man was gone for a long time, and when he finally returned to the pigpen it was
without a receipt.

"What's the problem, son?" asked the old man.

"I went up there just like you said," recounted the man from the city, "but your wife was too busy to give me a receipt."

"Too busy doing what?" wondered the farmer.

"Well, sir, I'm not exactly sure," stammered the man, "but I think she's weighing the postman."