A policeman pulls a guy over for speeding and walks up to the window of the culprits car. As he's reaching for his notebook and remonstrating with the driver, the copper flails away at some bothersome flies
"Damn flies" says the policeman
"Yes, they're a nuisance this time of year. They're very fond of buzzing round a horse's arse" said the driver.
"Now, sonny I hope you're not comparing an officer of the law to a horses's arse?" answers the policeman, tersely.
"No sir" said the driver, "can't fool them flies though".
