Farmer's Pig

A farmer had five female pigs. Times were hard, so he decided to take
them to the county fair and sell them. At the fair, he met another
farmer who owned five male pigs.

After talking a bit, they decided to mate the pigs and split everything
50/50. The farmers lived sixty miles apart. So they agreed to drive
thirty miles each, and find a field in which to let the pigs mate.

The first morning, the farmer with the female pigs got up at 5 a.m.,
loaded the pigs into the family station wagon, which was the
only vehicle he had, and drove the thirty miles.

While the pigs were mating, he asked the other farmer, "How will I know
if they are pregnant?"

The other farmer replied, "If they're in the grass in the morning,
they're pregnant, if they're in the mud, they're not."

The next morning the pigs were rolling in the mud. So he hosed them off,
loaded them into the family station wagon again and proceeded to try
again.

This continued each morning for more than a week. The next morning he
was too tired to get out of bed. He called to his wife, "Honey, please
look outside and tell me whether the pigs are in the mud or in the grass."
"Neither," yelled his wife, "they're in the station wagon and one of
them is honking the horn."