Performer shows a solid metal ring and places it over the stem of a teaspoon. He holds the end of the stem and ask a spectator to remove the ring from the spoon. The spectator cannot do this (unless he breaks the spoon!), because the ring is too small to go over the bowl of the spoon.
Performer now covers the spoon with the ring on it with a pocket handkerchief, and has a spectator hold the end of the stem through the handkerchief. Asking the spectator to hold the stem firmly, he gives the spectator’s hand a smart tap. The ring falls right off the spoon.
 
The spoon is removed by the spectator from under the handkerchief, - there is no ring on it. The handkerchief is shown freely on both sides, and the spectator can examine the ring and spoon to his heart’s content.
 
An amazing penetration, which you can present as a demonstration of mind over matter in the tradition of Uri Geller, or as an "impromptu" magic effect.