Plead not guilty get a free public attorney and say you sneezed and he thought you spit all over the ground. /thread
or request that they prove it was your spit by requesting a DNA test. Make it like the case of the century type deal...
Tuberculosis caused a lot of hysteria and led to many places making it illegal to spit in public as thats how it was believed to be spread. I'm sure there are places that just never got around to striking it from the books.