Does your car have a rear windshield wiper? Here's an easy way to communicate with traffic behind you.. Smiles + Wiper = the Swiper. Might make it a thing if it doesn't exist yet.
Ah - looks like it's already a thing. "Wiper Tags". Not too many options with words I guess because it would rotate upside-down partially. (?) https://wipertagstore.com/
Ah - looks like it's already a thing. "Wiper Tags". Not too many options with words I guess because it would rotate upside-down partially. (?) https://wipertagstore.com/