You present a deck with 4 cards that you show one by one.
There are 3 cards with dots, and a figure.
You explain that this card is a "vampire card" and that it sucks blood of the other cards.
Put the vampire card on another card and instantaneously, this card become white on both sides. The vampire card sucks the colors.
Retry with the other cards, the same miracle" happends.
Explain finally that vampires don't exist, and show the vampire card. Now it is blank too !