When I had dental braces such things were completely normal. I'd wake up on a wet pillow every morning and sometimes even drip like that guy. Maybe he has a toothache or his prosthesis isn't sitting well. Rabies makes you foam at the mouth not drip.
Oh look at this, a rational view being shared on Politics and Society based on something thinking with their brain. Isn't that something.
Everyone knows that something like this could happen, and the person probably assumes if they attempted to clean it it will cause more of a fuss. It probably looks worse because it's a picture by the way, I doubt this is something that was GUSHING out of him.
Relax folks.