The magician shows a pan full of water with five toothpicks in the shape of a pentagon.
The magician takes his magic toothpick and dips it in the center of the pentagon. The five toothpicks fly apart, breaking the pentagon!
Someone from the audience says... Oh, that's just what happens when you do that, it's not magic. The magician arranges the five toothpicks back into a pentagon and hands the person in the audience the magic toothpick. The person dips it in the center. Nothing happens. It really was magic!
Dip one of your toothpicks in liquid dishwashing soap. Set it aside for now.
Make sure your pan is clean. Rinse it well with water. Fill it quite full of water (but not so full that you're going to spill it).
Arrange the five SOAPLESS toothpicks in the shape of a pentagon. Make sure the tips of the toothpicks overlap so your pentagon stays together. This can be a bit of a challenge the first time you do it, so practice arranging the toothpicks at home a few times first and consider arranging them while the audience is seating itself.
Now, when the audience is settled, let them look at the pentagon. They may have to stand to do this or you may want to do the trick on the floor with the audience around you in a U-shape.
Tell the audience that you've arranged the toothpicks into a special five sided shape called a pentagon and that you're going to cast a spell on the sixth toothpick to imbue it with some of your magical force so it will be able to break apart the pentagon. (big words always impress an audience *grin*)
Take out the sixth toothpick (the one that was dipped in dish soap) and wave your hand over it while chanting some magical words. Close your eyes and frown a bit so it looks like you're working on putting your magic into the toothpick.
Words you could chant: Alaka penta Abraka magic
Now, dip the magical toothpick into the center of the pentagon (Make sure you dip the soapy end in the water and try to get it as close to the center of the shape as possible -- the soap shouldn't be visible anymore). The five toothpicks will fly apart.
If you have a non-believer in the audience, offer to let them try the trick. Arrange the pentagon in the water again and hand them the magic toothpick. Let them dip it in the center. It won't work!
If the audience asks you to do the trick a second time, just tell them that it takes awhile to recharge your magical force. You have to rest before you can put more of it into a toothpick, otherwise you could lose your magic forever!
Throughout history, a lot of 'magic' has really been science disguised with a few silly words. This is one of those tricks.
All things (including water) is made up of tiny things called molecules). Water molecules like each other and stick together (that's why when a bit of water falls on a table or window, it blobs together in a little droplet).
The surface of the water has a layer of clingy molecules on it -- this layer is called the water's surface tension. The toothpicks were nice and flat so they were floating on this layer.
Remember that we dipped the sixth toothpick in dish soap? That's the real trick to this trick. The soap molecules break the surface tension of the water. This effect spreads out in an ever widening ring (like ripples in the water when you throw a rock in a lake). The molecules originally holding the toothpicks break apart. The molecules farther away from where you dipped the toothpick still have their surface tension (for a little longer) so they pull the toothpick toward them. Of course, eventually the "ripples" of soap hit those molecules too.
Once the soap is in the water, the surface tension won't come back. That's why the audience member couldn't recreate the trick. It will only work once and then you have to clean everything up and use new toothpicks to do the trick a second time. That's also why you have to be careful that your pan is well rinsed before you do the trick.