These things used to be EVERYWHERE. Businesses used to brand them and pass them out like business cards.
Vintage
A community dedicated to anything vintage; tools, ads, movies, clothing & accessories, furniture, or anything else that fits the description of vintage
Milk money?
Edit: oh, like lunch money? I don't think I've heard to that referred to as milk money before if that's the case.
Dunno, ours was free before THATCHER MILKSNATCHER
I've literally never seen one before. What country and decade are these from?
USA for sure. I had one as a kid. It would have been about 1974 that I specifically remember another kid having one and knowing I wanted one too. We were in a gymnasium playing that game that involved all of the kids holding onto a big parachute and making it go up and down and jumping underneath it when it came back down. If you're in the US, you should know that game. It was a good day.
We used to make those in shop class.
How? Not joking. They're were molded one piece rubber. Your shop must've been cool.