The Setup

Tear off the edges of a sweetener packet and dump out the contents. This should leave you with a sheet of thin paper with a crease down the middle. This will be your "target." Set up your target a foot or so away from your outstretched arm, making sure to keep it as precariously balanced as you're able (the easier it is to knock over, the better it works).

Next, put on a show of slapping your face and rubbing your cheeks to "build up a charge", and finally, after rubbing your left cheek with your right hand, keep your hand wide and flat as you swing it in a wide arc from your face, eventually ending up pointing at the target.

If you do the move correctly, you will have generated a gust of air that will take a couple of seconds to reach the target. Once you have your timing down, it will appear that you simply point and "fire" your finger gun to knock over the target. It'll take some practice to get it down, but once you've got it, it's a blast!

Here's the best part: your friends will want to know how it's done. Explain that it's all about the static electricity generated by rubbing and slapping their face. The harder they try, the funnier it gets.