Someone who has a very disfigured face, is very unattractive, and looks like they give out goldfish if you throw a ball into a glass. Or if they work at McDonald's.
"Hey Carl, I was fucking this chick doggystyle, and she turned around, and WOAH, carnival face."
a person who has multiple deformities, wrinkles, dented face, and unproportional facial features. hence a carnival worker or carnie.
"Hey Carl, that girl has carnival face."