"Farmer and his..." joke

Farmer and his Pigs:
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 himself. So he loads the pigs into his truck, drives them
out into the woods, has sex with them all, brings them back and
goes to bed. Next morning, he wakes and looks out at the pigs. Seeing that
they are all still standing around, he concludes that the first try didn't
take, and loads them in the truck again. He drives them out to the woods,
bangs each pig twice for good measure, brings them back and goes to bed.
Next morning, he wakes to find the pigs are still just standing
around. One more try, he tells himself, and proceeds to load them
up and drive them out to the woods. 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 out and tell him if the pigs are
laying in the mud. "No," she says, "they're all in the truck and one of
them's honking the horn."