Tell your audience that you are going to make a quarter disappear right before their eyes.
Put a quarter down on a table, then place a salt shaker on top of it so that the bottom of the shaker completely covers the quarter.
Cover the salt shaker with a handkerchief.
Say some magic words (or sprinkle some imaginary fairy dust) over the handkerchief and salt shaker.
Keeping the salt shaker covered, lift the handkerchief and salt shaker off the quarter.
Express amazement that the quarter is still there. While doing so, move the handkerchief and salt shaker toward you, allowing the salt shaker to drop into your lap.
Maintain the handkerchief's shape with your hand as though the salt shaker is still there. The audience should be too focused on the quarter to notice.
Move the handkerchief (which maintains the salt-shaker shape) back over the quarter.
Slam the handkerchief down with your free hand, revealing it to be empty. As you do so, say, "Oh, well. I'll just make the salt shaker disappear instead."