A really strong piece of mentalism that is impromptu and can be performed literally in every single performing situation is not too easy to find. This, however, fits the bill beautifully.

Effect: The mentalist places a business card onto the table. The audience is told that there is a prediction underneath the business card, but that it will not be shown to them until later. The performer reaches into his pocket (or wherever) and brings out three invisible coins: a nickel, a quarter, and a dime. The spectator is told to imagine that she sees them. The performer lays the imaginary coins in a row on the table.

The spectator uses her imagination to select one of the coins. Let's say she selects the quarter. She then, using her imagination, flips the invisible quarter into the air. She then calls out whether the quarter landed heads or tails side up. Say she picks heads. The card is then removed, and underneath the card is a quarter! Not only that, but the quarter is marked to prove that the mentalist knew the outcome of the coin toss from the beginning!

This is David's beautiful approach to Max Maven's "Positive/Negative". Several changes have been made from the original routine. The features include:

No switches of any kind
Only one prediction
Nothing is written
No gimmicks of any kind
99% impromptu (all you need is any kind of cover such as a card or an opaque tumbler, any coin, and a Sharpie Marker)
Nothing is stolen away
Nothing is hidden
Absolutely everything is examinable and ungimmicked
Everything may be given away to the spectator to keep
Perfect for walk around, table hopping, formal close up, and even on STAGE!
No sleight of hand whatsoever
Only one coin is under the cover

You are going to love this and use is every chance you get!