"State Troopers blooper" joke

The following is another goodie related to me by my mom years ago. It's another one of those that's just a little too good to be true. Though the veracity may be questionable, it's a great story.
Preface: Policemen, firefighters, etc. used to have annual dinner-dance type affairs (they were referred to as "The Policeman's Ball", etc) to raise money for the local constabulatory. The individual officers were responsible for selling tickets to the event to those on their beat.
And now, the story:
A woman was driving down the road one day only to find herself behind a horse trailer being pulled by a pick-up truck. As they were driving along, the back door of the horse trailer came loose and swung open, exposing the rear end of the horse inside.
Eventually, gastric and bowel processes completed, the horse's tail lifted and - voila - the woman's windshield was covered in horse stuff.
Now the woman's first instinct was, of course, to turn on the windshield wipers. Unfortunately, this only made the situation worse and as the woman tried to gain control of the car and keep it on the road, she heard a siren.
Craning her neck out the window to steer the car onto the shoulder, she noticed that the siren was sounding from directly behind her and followed her onto the shoulder.
Sitting in her car, trying to regain her composure, a state trooper came alongside and asked the woman for her license and registration. Now, it was readily apparent from even a cursory glance, what had happened to the windshield of the woman's car and she was shocked that the trooper appeared so callous and had not even enquired as to her safety.
"What do you want my license and registration for?" asked the woman.
"You were driving erratically," replied the state trooper.
Now, almost apoplectic, the woman began fumbling through her purse. As she presented the requested documents to the state trooper she asked, sarcastically, "I suppose you want to sell me a ticket to the state trooper's ball, also."
The state trooper fixed her with a long, hard gaze, drew himself up to his full height and replied, "Ma'am. State Troopers don't have balls!"
After a momentary pause, the trooper's face turned several shades of red. He handed back her license and registration, strode back to his car and drove off.