A farmer got pulled over by a state trooper for speeding, and the trooper started to lecture the farmer about his speed, and in general began to throw his weight around to try to make the farmer uncomfortable. Finally, the trooper got around to actually writing the ticket, and as he was doing that, he kept swatting at some flies that were buzzing around his head. The farmer said,
"Having some problems with circle flies there, are ya?" The trooper stopped writing the ticket and said, "Well, yeah, if that's what they are. I never heard of circle flies." The farmer said, "Well, circle flies are common on farms. See, they're called circle flies because they're almost always found circling around the back end of a horse." The trooper nodded and went back to writing the ticket.
Then after a minute he stopped and said, "Hey, wait a minute... are you trying to call me a horse's ass?" The farmer replied, "Oh, no, officer. I have too much respect for law enforcement and police officers to even think about calling you a horse's ass." The trooper said, "Well, that's a good thing," and went back to writing the ticket. After a long pause, the farmer said, "Hard to fool them flies though."