Soon we are twenty-one people circulating thirty bills. Everybody notices that the method is working: each one now must grab another bill from Left before he has a chance to give his bill to Right.
A few minutes later, I stop for a moment to pick up the pen that I dropped on the floor. While doing so I discreetly pocket the bill that Left just handed me, and I immediately resume the play. With the bills in motion, no one can count them and notice that now there are only twenty nine going around.
No, wait, that guy across the circle is angrily staring at my pocket, he noticed my trick! I am done! But, instead of blowing the whistle, the scoundrel winks at me, pauses for a moment to blow his nose, discreetly pockets the bill from Left too, and goes on playing. Phew!
But I'd better play safe. I tell everybody, "sorry folks, I must pick up my turtle at the gym, you carry on without me." And I walk out holding high "my" bill, that I just got from Left. That scoundrel does the same. The other nineteeen guys thank me for the great opportunity and keep on passing the remaining twenty-six bills around, already thinking on how they will spend their profit.
Advantages: I make 100 dollars.
Disadvantages: I don't know yet, let's see how that Bitcoin thing ends.
