What is a challenge coin? (Wikipedia)
A challenge coin is a small coin or medallion, bearing an organization’s insignia or emblem and carried by the organization’s members. Traditionally, they might be given to prove membership when asked and to enhance morale. They are also collected by service members and law enforcement personnel. Historically, challenge coins were presented by unit commanders in recognition of special achievement by a member of the unit. They could also be exchanged in recognition of visits to an organization.[1]
Modern day challenge coins may feature popular culture attributes[2] or organizational values.[3] Modern challenge coins are made in a variety of sizes and are often made using popular culture references, including superheroes and other well-known characters in a way that creates a parody.