Challange Coins?

As a 16 yr and some change Marine I can tell you a Challenge Coin is a big deal. Every unit, at least the good ones, have their own coin with the unit logo on one side and the Eagle, Globe and Anchor on the other. Tradition goes you can "challenge" a current member of your unit and/or former member at the bar...if he has his coin, you buy. If he doesn't, he buys. I have about (12) of them on my dresser and I am darn proud of each one. Often you are given one by a visiting senior Officer or as a momento by a unit if you support them during a deployment, operation, etc. I carried mine in my pocket everyday during my most recent deployment to Iraq as did every Marine in my unit.