Challenge coin

From Milipedia

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[edit] Challenge Coin

Challenge coins are medallions made by military units, commanders, federal agencies, organizations, or any other entity that wants a memorbilia of what they achieved or stand for. These are popular to collect and have vastly changed military collectibles around the world. Today the trade for a few dollars or hundreds of dollars.

One way challenge coins work is a group challenge. By presenting your coin on a table top or floor people acknowledge your "challenge" to see if there is anyone that doesn't have a coin with them. Thos that do not have a coin are usually held to buying a round of beer or soda for the rest of the group. However, if everyone has one the person that initiated the challenge has to buy the round. This is why they are called challenge coins.