Grab a beer bottle and some straws for this simple trick!
The Setup: grab two straws and an empty beer bottle. On the straws, mark a "no man's land" of about 2-3 inches in the middle.
The Rules: Neither you, nor anything else is allowed to touch anything in this "no man's land" area on either straw. Each independent side of each straw can touch either you (your fingers), or the beer bottle... but no one side can touch both you and the bottle at the same time.
The Challenge: Staying within these rules, use the straws to pick up the bottle off the table, carry it over the wall, and land it safely on the other side.
The Secret: After they've made a mess of their attempts, reveal the truth: You only need one of the two straws! If you crease a "hook" into one of the sides, and start to slide it down the neck of the bottle, it will wedge itself in. Once this happens, you can pull up the straw, and the bottle along with it!