A blue-backed deck is spread on the table. Three red-backed cards are shown and kept in the hand. The faces of these cards are not yet shown. A spectator FREELY selects a card from the deck. The selected card is shown and revealed : It is ( say ) the 8 of spade. The three red-backed cards are seen to be the other three cards of the same value to form a four of a kind! The deck is spread face up and all the cardsare seen to be ( say ) 2 of heart.

No roughing fluid, Easy to do.
Compete with special deck.