They must have been the most commercially successful bits of toxic positivity merch I've ever known. Back when they were a thing, your chances of getting in a road-rage based auto accident spiked each time one of these was on the back of a vehicle in motion:
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They seemingly vanished off the face of the Earth, and good riddance.
They didn't fucking work. I was still unhappy and worried
Telling people not to worry and to performatively be happy was just an assholish flex all along.