Don’t buy caustic drain cleaners at the store. You’ve already got what you need to clean a stopped up drain. Pour a cup of baking soda into your drain. Then pour about 1/2 cup of vinegar down the drain and cover it with a plate. The baking soda and vinegar will combine to create a foaming effect, and the plate will prevent any bubbles (and gunk) from rising into the sink. Let the mixture sit for half an hour, and then flush it with hot water for several minutes until the drain runs clear. When performed regularly, this method works as a preventative measure against clogs and build-up.