Gringo

The word Gringo can be a positive or negative term, depending on the context. The word gringo is used to refer to any sort of immigrant or foreigner, especially someone from the United States. Popular myth traces the word to the Mexican-American War (1846-1848) or how the Mexican text books would have it as, La invasion Norteamericana. When the Army invaded Mexico, one of the songs the soldiers often sang began: "Green Grow the Rushes-O" and the first two words were supposed to have become the term for the soldiers.
Some scholars actually say that the term gringo actually evolved from the Spanish word griego (greek), which was sometimes used to mean "foreign and unintelligible speech." This was extended to mean "foreigner" or speaker of gringo.