Astounding! Fill this transparent glass with water. Cover the glass with your hand, and turn the glass upside down. Of course, your audience will expect the water to pour out, but the liquid remains in the glass!
Is it magic? Is it science? Whatever you call it, IT'S IMPOSSIBLE!
Make sure to thoroughly rinse and dry the plastic tumbler as soon as possible after each use. DO NOT use a scrubbing pad or any type of abrasive cleanser on the plastic, as it will cause scratches and make the tumbler look cloudy.