Neat idea. But how do you convince your friends to do this? A: I call heads. <flip> B: It came up tails! I win! A: No, wait, we're not done yet. We need

Neat idea. But how do you convince your friends to do this? A: I call heads. <flip> B: It came up tails! I win! A: No, wait, we're not done yet. We need to flip it again, if it comes up tails, we start over. B: What? No, give me my doughnut!