Carefully pour a mixture of 2 cups of baking soda and 1 cup of white vinegar down the drain. The chemical reaction will be so intense, it'll be like a mini-volcanic eruption!
But What If I'm Dealing with a Clog? Ah, that's a different story.
For the Plunger Enthusiasts out there, don't forget to use a plunger with a good grip and some elbow grease.
Or, you know, just call a professional.
Stay dry, stay happy.