Fusion Coins by Dr. Michael Rubinstein.

Routines with impossible objects as their surprise ending always over-perform. This is one of Michael Rubinstein’s favorites.

The basic routine features you handing two coins to your friends for examination (a Half Dollar and a Penny) as you explain the different metals they are made of.

You then place the Penny on top of the Half Dollar and after a little squeeze the penny sinks into the quarter and is fused inside. The odd new coin can then be examined.

You pick up the coin, give it a little shake and the penny falls out leaving everything examinable and ordinary.

Also includes some quickies by Meir Yedid using the coins.