OOBLECK. This stuff is amazing. Mix 2 cups of cornstarch and 1 cup water in a bowl. To color oobleck, add a few drops of food coloring to the water before adding to the cornstarch. Takes some effort to mix the water and cornstarch. If you quickly smack oobleck with your hand it immediately turns into a solid, instead of splashing or moving. If you slowly move oobleck it reacts like a liquid.
Put a tiny bit of toothpaste into a small cup, mix in one teaspoon baking soda plus one teaspoon of hydrogen peroxide, and half a teaspoon water. Thoroughly mix then brush your teeth for two minutes. Remember to do it once a week until you have reached the results you want. Once your teeth are good and white, limit yourself to using the whitening treatment once every month or two. - And to think I almost shelled out $40 at the store for some whitening strips!