Totally out of toothpaste? Don't sweat it. Turns out, baking soda is good for more than cleaning a sink or building a science-project volcano. It can clean your mouth and save the day. For this breath-freshening hack, all you'll need is baking soda, water, and your toothbrush. First, mix the baking soda with water until it becomes a thick paste. If the mixture is too thin, you may need to add more baking soda. Then, just top your toothbrush with the homemade paste and brush as normal. Your pearly whites will live to smile another day.