You and the mark each throw a set amount into the pot. The mark begins to shake 3 coins together in his or her fist. Asked to pick heads or tails, the mark picks heads. The coins are thrown on the table. If three heads show up, the mark wins; if three tails shows up, you win. If there is a mix of heads and tails, nobody wins and each party again throw more money into the pot. This back and forth continues until somebody wins.
The Outcome: You win 100% of the time!!!!