An old farmer was hauling a load of manure when he was stopped by a highway patrol officer who says, "You were speeding and I'm going to give you a ticket."

"Yep" says the farmer as he watches the officer shoo away a bunch of flies.

"These flies are terrible," the officer complains.

"Yep," says the farmer. "Them are circle flies."

"What's a circle fly?" asks the officer.

"Flies that circle a horse's ass," says the farmer. "Them are circle flies."

"You wouldn't be calling me a horse's ass, would you?" the officer asks.

"Nope... I would never do that" the farmer says. "I have too much respect for policemen to even think about calling you a horse's ass."

The officer says, "Well that's a good thing,” and goes back to writing the ticket.

After a long pause, the farmer says, "Hard to fool them flies though."