Knock their socks off!
Show this deck of white cards with many different printed shapes and symbols.
On a slip of paper, write your prediction of which symbol you think will be chosen.
Wrap the deck of cards with a rubber band and hand them to your spectator.
Ask him to lift up on the edge of the deck so he can peek at any one card, and remember the shape illustrated on that card.
When he has chosen a card, ask him what the symbol looked like.
Your prediction will match the symbol chosen!
This is a very popular ESP effect because it is SO EASY and SO QUICK.
Plus, there are many more symbols than just the usual five ESP symbols, so it is more interesting to the spectator.
And this is the IMPROVED version!
You get more cards with even more symbols so the prediction looks even MORE impossible!