Gringo

A nickname Mexicans use to refer to Americans. It seems many Americans think it's offensive, but as far as I've heard being said in Mexico, it's just a casual way to refer to Americans. Btw, the term seems to almost exclusively be used to refer to Americans for some reason.

El nuevo compañero de la escuela es gringo. Apenas se entiende su español.

(The new classmate is gringo. I can barely understand his spanish.)