I found this one out by accident. Note the big Do not swallow thingy on the back of the bottle.

One day i was removing the top layer of skin from the inside of my mouth (using listerine as it was intended), while i had a strep-throat infection. (I had a Doctors appointment for the next day, we could see the white pussy things in the back of my throat, along with an awful sore throat and cough). Well i coughed a little bit and some listerine went down, not that much, maybe a tablespoon. It felt a little weird, but i woke up without a sore throat, no more cough, and no more visit to the doctor. I doubt it was the healithiest way to cure it, but it worked.

Another use for listerine (more so the yellow kind, as thats the original) is as disinfectant instead of Hydrogen Peroxide. Put a little on a cotton swab or gauze and dab away, then rinse with clean water. Make sure it is not an open wound as it is a toxic chemical if it gets into your blood stream.