TWO METHODS:
One with ESP cards.
Second with Bicycle Playing Cards.
?
Two spectators are invited to take part in an experiment of sorts, a test of coincidence if you will. Each is handed a pack of 5 ESP Cards, and told to mix them. After both feeling satisfied with their shuffling, they are asked which of the two is usually the decision maker in the relationship, after this is settled upon (which is usually quite fast) the chosen participant is invited to deal their cards onto the table -face 2 down - in a row. After this, the second participant places their cards onto the table, starting wherever they want, in the reverse order to their partner. After deliberation, the pair are asked which of the five cards they think is a matching pair - if any - and they both turn over their cards to reveal that they match.

The performer (magician, Mentalist, compare, MC - whoever you are) then tells them the odds of this happening are quite low. And invites them to turn over each of their other cards in turn -revealing that that have - in fact - matched each other 5 for 5. The performer (you) then tells them how I!possible this is, congratulates them, and sends them back to their seats.