Challenge Coin
A coin earned in military service. (Command Coin, Deployment Coin, or Rank Position Coin.) Used to challenge other military members or veterans in a bar. If you presented with a coin and don't have one on you then you are expected to buy them a drink. If you have a coin to respond back to them with then they are expected to buy you a drink. Hence completing the challenge.
Everybody had a challenge coin but me at the bar tonight.
Challenge Coin
A Challenge Coin is a quarter-size bronze disc that one cadet can give to another cadet. If a cadet gets one, he must do whatever the other cadet challenges him to do.
Matt gave me a fucking Challenge Coin -- I have to give a blowjob to any other cadet in my graduating class who wants one, but I have to ASK if they want me to suck their dick!
Challenge Coin Tasks
Challenge Coin Tasks are the things you have to do to fulfill your obligation to the cadet who gave you the Coin. Mine was to ask each cadet in my graduating class if I could suck their dick and swallow their load while I jacked off and blew my load.
When I go to the cadet showers every morning, I look for guy's who haven't taken care of their morning wood and are walking around with raging boners. Then I fall to my knees in front of their hard-on -- they usually say "go for it!" - I do and complete one of my Challenge Coin Tasks!