What a Turn Up - Harry Baron

Without showing their faces, you share out a small packet of cards equally between yourself and a spectator, and have them copy what you do exactly.

You pick up your face down packet and put it behind your back- the spectator does likewise;
You mix your cards behind your back - spectator does too;
You choose one of your cards and bring it out, still face down - the spectator duplicates your action;
You and the spectator exchange the single chosen cards with each other;
You take the spectator's chosen card behind your back, turn it face up and insert it anywhere in your face down pile - the spectator copies you'
You bring your whole packet out front, still face down, and the spectator does the same;
Now, you slowly spread out your cards - one card is face up - say, the Queen of Hearts. The spectator fans his cards and has, as expected, one card is face up also - to everyone's surprise, IT MATCHES YOUR CARD, THE QUEEN OF HEARTS!
Removing the cards from the fans, you say, "I know what you're thinking: 'all the cards are the same?!' - as you say this, you turn your fan of cards face up and continue, "Well, you are right!!" - ALL THE CARDS ARE THE SAME, THEY ARE (for example) ALL THE SIX OF CLUBS! If the spectator doesn't turn over his fan, take it from him and turn it over - ALL HIS CARDS ARE ALSO SIX OF CLUBS!
 

Remember! You picked your card first, you brought out your packer from behind your back first, you fanned your cards and showed your one face up card FIRST!!!