^A blond highway police stopped a car that just happened to be
   driven by another blond. Police demanded the driver to show her
   drivers licence, but the driver said that she did not know what
   a drivers licence was.

   - It is that rectangular thing where there is the picture of
   you, said the police.

   The blond searched frantically everywhere in the car, until she
   found a rectangular mirror in the glove compartment. She also
   saw to her immense satisfaction how there was her picture in it.

   She proudly handed the mirror to the blond police, who retorted
   immediately.

   - Why did you not say in the first place that you are a police
   too!^