Circle Flies and the horse's ass.

 And this reminded me of this old joke:

An older farmer got pulled over by a brand new state trooper for impeding traffic, (moving slower than the normal flow) and the trooper started to lecture the farmer about his driving, and it was this particular officers nature, to try to make the alleged offender feel inferior.
Finally, when he didn’t get a rise out of the respectful older man, the trooper got around to writing out 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 them circle flies?”
“Well, yeah if that’s what they are, I’ve never heard of circle flies”.
So the farmer says, “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 says, “Oh,” and goes back to writing the ticket. Then he stops and says, “So, are you trying to call me a horses ass?”
The farmer says, “Oh no, officer. I have too much respect for law enforcement and police officers to even think about calling you a horses back end.”
The trooper says, “Well, you need to watch what you’re insinuating,” and goes back to writing the ticket.
After a long pause, the farmer says, “It’s damn near impossible to fool them flies though.”