This is a specially prepared pack of cards which allows you to perform some fancy card flourishes with much greater ease, and far less practice, than if performed with a normal pack. It allows you to give an impression of much greater skill than you really possess.
The King of Hearts is placed between two 10 of Spades. Suddenly the King is turning upside down. Then one of the 10 of Spades changes into King of Hearts and the colour of the backs changes from black to red. The spectator is confused. But you are fair and want to help the audience in keeping....