A cowboy gets pulled over by a police officer for speeding. The trooper starts to lecture the cowboy about his speeding. Finally, the trooper got around to writing out the ticket. As he was doing that, he kept swatting at some flies that were buzzing around his head.

The cowboy says, "Y'all havin' some problems with circle flies?"

The trooper reponds"Well yeah, if that's what they're called. But I never heard of any circle flies."

"Well sir," the cowboy replies, "Circle flies hang around ranches. 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. But, a moment later he stops and says, "Are you callin' me a horse's ass?"

"No sir," the cowboy replies, "I have too much respect for law enforcement to call you a horse's ass."

"Ok" the trooper says and goes back to writing the ticket.

After a little pause, the cowboy says, "Hard to fool them circle flies though."