Originally Posted by
Cletus
I think it was done by some marketing team for companies that produce them or sell them online. A lot of people collect them, even those of units in which they never served. If you look, you'll see them now for all kinds of things. They have become so widespread that I think for most people, calling them "Commemorative coins" would be more appropriate since a lot of them today commemorate specific events rather than military units. "Challenge coins" may be the popular term for them at the moment, but I would be willing to bet that the majority of people who collect them will never get caught in a "coin check".