Coin matching and finger flashing were among the first formal games to arise in the history of gambling. The class of Morra games extends back to the pre-Christian era, although not until comparatively recent times have game-theoretic solutions been derived.
I know it's sappy, but I bet there's a market for civility and niceness out there that, while probably not as titillating as a junkyard scrap between shirtless adversaries, it'd sure be healthier.