While driving on the highway, spotting an unmarked vehicle ahead that resembles a cop car. This sighting causes you to slow down and remain behind the car until you figure out if it is safe to pass. The most notorious models include the Ford Crown Victoria and the similar looking Mercury Marauder, and nowadays can include the Chevrolet Impala, Dodge Charger, etc.
Guy: What are you slowing down for dude?
Driver: Theres a Crown Vic up there
Driver: Possible pig bro
Guy: Oh word good call