The magician show two Plexiglas plates between which there is a 10 euro bill. The two plates are held together by two rubber bands.
Then a spectator secure the bill with a padlock. The padlock is passed through the holes in the plexisglass plates, as well through the bill! The bill is punched and cannot be longer removed between the plates without tearing it !!! The audience may also sign the back of the bill.
Now you use a second 10 euro bill and sign it.
You cover all under a cloth with spectator’s bill secured in the plexiglass plates with your bill.
After a moment you bring your hand back under the cloth.
Suddenly, your bill is now inside and backed by the lock between the plexiglass plates, while the signed bill from the spectator in now held in your hand. Both bills have changed of place!
Then you can open the lock, and give all for examination. Although both bills have a hole, but are otherwise completely unharmed, so that this magical trick of changing place to another cannot really be explained!