This effect always gets good reactions. Probably because of the surprise when they think you are about to do one amazing thing then you suddenly do something totally unexpected. When seemingly failing to make a coin vanish
from under a salt shaker, you slam the salt shaker with your palm and it slips straight through the solid tabletop.
This effect works because the salt shaker is covered with paper napkins; these napkins are able to hold the shape of the salt shaker long after it has gone.
While sitting at a table with everything in place (Saltshaker or glass, and paper napkins), ask someone if you can borrow a coin to do some magic. Say that you are going to make the coin disappear, and place it on the table. Cover the salt shaker with a napkin or two so they take on the shape of the shaker. Photo 1.
Point to the coin and tell everyone that all you have to do is cover it with the shaker and the coin will vanish. This will draw everyone’s attention to the coin.
When you cover the coin with the salt shaker and napkin say, "All I have to do is click my fingers and the coin is gone". Click your fingers and move the napkin and shaker in towards your body to the edge of the table. Photo 2.
Once you’ve got the shaker in this position and everyone is looking at the coin (still on the table), drop the shaker into your lap keeping the napkin (still holding the shape of the shaker) in your hand.
Look annoyed that the coin did not vanish and say that you will try again (at this point drop your free hand underneath the table taking the shaker and holding it there). With your hand holding the napkin, simulate the motion of tapping the salt shaker on top of the coin counting "1, 2, 3", while doing this, your hand under the table actually taps the bottom of the table at the same time. This will create the perfect illusion that the shaker is still under the napkin.
On the count of three, stop for a moment and say, "Actually, how about this", and slam your hand down onto the napkin crushing the form of the salt shaker. Photo 3. Act as if you just caught the shaker from under the table
and bring it out to show that it actually went right through.
When handling the napkin, act completely casual as if the shaker is still in there. No-one will even be thinking about the salt shaker so its not hard to keep attention away from it.