Gringo

Gringo is a Spanish and Portuguese term used mostly in Latin America to denote foreigners, specially people from the United States, Canada, and UK. 
In Brazil, the term is used to refer to any foreigner, regardless of their ethnicity or nationality, even when it comes to other Latin-Americans.
Etymology.
The most supported theory is that the term originates from the word "griego" ('Greek'), used in the same way as the English phrase "it's all Greek to me". Some theories assert that the term originated in the Mexican-American War, when American troops sang a song which began with "Green grows..." such as "Green Grow the Rushes, O", "Green Grow the Lilacs", among others.