Have you ever wondered what it would be like to do a fail-safe magic trick? Magicians rarely share secrets like the one about to be revealed. This trick relies solely on your ability to fool a crowd. If you can keep a straight face and pretend you mixed up this trick with another, the crowd will beg for a repeat performance.
Cut a piece of tin foil long enough to completely cover your cup. The goal is to form the tin foil over the cup, while leaving an overlap around the cup on the table. Set up a table and chair so that you will face the crowd during the trick. Spread the tablecloth so that it hangs over the side of the table facing the crowd. You don't want the audience to see your setup.
Proclaim to the crowd that you intend to make a coin pass through the table. Pass the coin around the crowd so that they can see it's not a trick coin. Smirk mysteriously to make them focus on that coin. Place the coin on the table top. Look like you are pondering the placement of the coin and flip it over again. You want the audience to focus on placement of the coin.
Put the plastic cup over the coin. Put the tin foil over the plastic cup. Squish the foil around the cup to form a cup shape in the tin foil. Make sure you don't show any edges of the cup. This is setting up the audience for a switch.
Move the cup on the table around the area of the coin and say some magic words. Pull the cup up slightly and tilt it toward the audience. Move the cup back toward your lap in a fluid motion and drop the cup, leaving the tin foil-shaped cup. You have completed the setup. While the audience thinks they should have watched the coin disappear you've actually made the cup disappear!
Look perplexed that the coin didn't magically fall through the table and pretend the step again. Gently hold on to the tin foil cup form and place it over the coin again. Say the magic words and remove the tin foil cup shape. Make sure the top is tilted toward the crowd so that the missing cup isn't noticed.
Pretend to be mad and place the tin foil form back over the coin. Say the magic words and pound your fist down over the tin foil shape, flattening it. Proclaim that you must have mixed up your tricks, and that the cup was supposed to go through the table, not the coin.
Time things exactly so you can drop the cup to the floor at the same time that you pound the tin foil. Play along with the crowd. If you appear mad, the audience will think the trick has failed.
Use tin foil to cover the cup in this trick, as a napkin reveals the missing cup.