You will need:
Any 3 coins of your choice,
2 small envelopes (or something not clear that can hold a prediction)
a paper with a prediction of one coin and heads
a paper with a prediction of the same coin and tales.
a volunteer from the audience
preparation: put one of the envelopes in your one pocket, the other envelope in your other pocket. remember which pocket contains heads and tails. you are ready to begin.
you show 3 coins to an audience member. you ask them to pick one. they throw it up in the air and see which side it landed on. you pull an envelope out of your pocket and reveal your prediction. watch your audience's faces as they are amazed the two answers match.
how to do it:
pick an audience member out of the crowd. have them choose 2 coins. for instance, if the coin you picked is a quarter, and they choose the penny and the quarter, eliminate the other one. using magician's choice, make it so the quarter is the last one left. if you like, you can use more than three kinds of coins. tell them to flip the coin. if it lands on heads, take out the envelope that says heads. if it lands on tails, vice versa. your audience, and volunteer, will be AMAZED when your prediction matches your volunteers coin.