The Houdini disc

The magician shows a small, empty box and three disks: two green and one red. He tells the audience that he will call the red disk the "Houdini" disk, in memory of the world's most famous escape artist: Harry Houdini. After saying this, the magician places the red disk between the other two and encloses the three disks in the small box. He then asks a spectator to place their open hand, palm up, underneath the box. He gently taps the box, and incredibly, the red disk falls onto the spectator's hand! He then asks the spectator to open the box and check that only the two green disks remain. Just as Houdini did in the old days, the red "Houdini disk" has made the impossible possible.