car card

noun

1. a sheet of cardboard bearing an advertising message for display, as in subway cars, buses, and trains.
2. cardboard coated on one side only.

Example Sentences

Better yet, tell him you did then we he asks to see your car card as proof, hit him with a HIPPA lawsuit.

From Vox

Experienced advertisers have found that to use wordy arguments on a street car card is a mistake.

From Project Gutenberg