A farmer buys several pigs, hoping to breed them for ham, bacon, etc. After
several weeks, he notices that none of the pigs are getting pregnant and calls
a vet for help. The vet tells the farmer that he should try artificial
insemination. The farmer doesn't have the slightest idea what this means but,
not wanting to display his ignorance, only asks the vet how he will know when
the pigs are pregnant. The vet tells him that they will stop standing around
and will, instead, lay down and wallow in the mud when they are pregnant.
 
The farmer hangs up and gives it some thought. He comes to the conclusion that
artificial insemination means he has to impregnate the pigs. So, he loads the
pigs into his truck, drives them into the woods, has sex with them all, brings
them back and goes to bed.

Next morning, he wakes to find the pigs still standing around. One more try, he
tells himself and proceeds to load them up and drive them to the woods again.
He spends all day shagging the pigs and upon returning home, falls listlessly
into bed.

The next morning, he cannot even raise himself from the bed to look at the
pigs. He asks his wife to look and tell him if the pigs are laying in the mud.
"No," she says, "they're all in the truck and one of them is honking the horn."