The Bet: 

Place two quarters on the table with a dime between them. Balance a glass mouth down on top of the two quarters while completely covering the dime. Challenge a spectator to free the dime without touching any of the objects.

The Secret: 

The method relies on performing this little stunt on top of a table covered with a cloth. Scratch the tablecloth as in Figure 1 and the dime will scoot towards your finger while freeing itself from the glass cover. This works best if you’ll scratch in alignment with the threading of the tablecloth.

Just like a pogo stick, a hula hoop or silly putty you don’t need an audience to have a good time with this one. Just play with it and have fun.