What Would The Actual Effects Of This Be?

So you've managed to chug some drain cleaner (base) and your brilliant solution is to chase it with battery acid? The logic is technically sound—acids and bases DO neutralize each other—but your stomach is about to become a chemistry lab explosion complete with heat generation and salt formation. The exothermic reaction would release enough energy to make your esophagus feel like a supernova, plus you'd be creating water and various salts that your body absolutely did not ask for. Pro tip: the pH scale might balance out on paper, but your internal organs aren't beakers and they definitely didn't consent to this titration experiment. Call poison control instead of playing mad scientist with your digestive tract.