A card is selected by the spectator. The spectator shows the card to the audience and hands it back to the magician. The magician then takes the card and tears off a corner and hands the card back to the spectator. The corner piece is shown to the audience by the magician. Magically the corner piece vanishes from the magicians hand.
The magician points to an ordinary egg that has been sitting on the table the entire time. The magician cracks the egg open and inside is the corner piece of the selected card.