1: Challenge is made by displaying coin on a hard surface.

2: Response is made by displaying coin on a hard surface within 10 seconds of Challenge (+ / - 30 seconds).

3: Unsuccessful Response obligates you to the challenger for the drink of their choice.

Among elite units, the tradition is prevalent to carry some type of device which readily identifies unit members, past and present, and also provides the opportunity for an inspection of the unit's esprit de corps and purpose.

The military coin, minted in a number of metals, including sterling, is approximately two Inches in diameter. The coin carries the motto's or slogans of the particular unit manufacturing it. In addition to any official motto is usually a likeness of the unit flash or  crest.

Nearly every Special Forces unit has minted its own version of the  coin; however, the 10th Special Forces can be credited with fostering the tradition for a unit coin. In July 1969, Colonel Vernon E. Green, Group commander, designed and had manufactured the 10th Group coin. On the obverse, or front, is the inscription: "10th Special Forces Group (Airborne) 1st Special Forces." In the center of the coin is the Trojan Horse crest, the original SF crest worn during the 1950s, and below, the words "Trojan Horse." The reverse side is inscribed with the Special Forces motto "De Oppresso Liber" and "The Best."

Once the 10th Group coin was minted, the tradition began, calling for each Group member, past and present, to procure and carry a coin at all times. In addition to active or former Group personnel owning coins, they have been presented to friends and foreign Special Forces soldiers at the close of joint country training, as momentos.

The actual history of the challenge initiated by one unit member to another by demanding to see his coin varies greatly. According to legend, the original coin check was done only by the senior man present, who did it for the sole purpose of ensuring each man's team spirit (in which case, all would be carrying a coin). The purpose of this drill was to check morale.

Nowadays this is primarily a dare, by extracting the coin and slamming it down onto the tabletop or tossing it to the floor. The loud "ping!" produced by the bounding coin is a challenge to all present to produce their coins, or end up buying a round of drinks. This method of the "coin check" is the most prevalent today.

There have been many attempts to established a set of rules for the coin challenge to ensure uniformity. Regardless of any "coin regulation," most prefer to carry their coins, not only to show their pride with their, but also to save money on drinks they may have to buy if caught without it.