Create a little something from nothing, then hand it to a pal.
What to do: Extend your hands as if you're holding a ball. Have a friend place her hands over the back of yours, then tell her to press firmly, as shown.
As she does, press outward so that your hands and hers stay in the same position. Tell her to gradually increase the pressure, while you push out.
Count to 60 in your head, then have her close her eyes and slowly reduce the pressure. As she does, move your hands away.
The payoff: For a few seconds, she'll feel as if she's holding an invisible ball.