Sketch-Wagon

n. A suspicious automobile, often a police car. The word "sketch-wagon" is most often used by people participating in illegal activities, such as speeding or running a red light, and is mostly associated with smoking marijuana.

(Can also referred to as "Sketch-Mobile.")

Michael ran a red light and thought he'd gotten away with it, when a sketch-wagon appeared out of nowhere and pulled him over.

chillroad

to drive down a peaceful road or street while under the influence of marijuana.

We went chillroading after we had just inhaled a fatty. John and I decided to chillroad while we smoked a bowl.