Rub a balloon along your hair about a dozen times. (You'll know it's enough if the hair on your arm stands up when you bring the balloon near it).
Turn on the faucet so you have a very small stream of water.
Hold the balloon near the water (but don't touch the water with the balloon).
Your hair charged the balloon with negative charges. These attracted the positive charges in the water, causing the water to move.
The picture doesn't do it justice - you really need to try this one yourself!
You could also use a rubber comb instead of a balloon. But, I found that the balloon worked even in really humid weather, and the comb didn't.
