plain wrapper 

'70s CB slang for an unmarked police car, usually used with the color of the car between "plain" and "wrapper."

There's a plain wrapper, blue, up at mile marker 128.

plain wrapper by oneoldgeezer November 6, 2007

plain wrapper 

the po po, 5-0, the police, smokie or cops.

That plain wrapper just pulled someone over.

plain wrapper by team norf souf August 9, 2006

plain white wrapper

An unmarked police car with a radar gun. Also known as a Hemorrhoid with a Polaroid, or Kojack with a Kodak.

"Careful on your way in to town, there is a plain white wrapper sitting beside the road checking speeds"

plain white wrapper by Meatman128 October 1, 2013