I figured I’d better address this one, since that term my show up in my blog from time to time. I imagine that most people are familiar with the term, though some may not be. ‘Gringo’ is a term used in Mexican Spanish to refer to a white North American.
The origin of the term is the subject of much debate. If you’re interested, check out the Wikipedia entry on it. Where we are, the most common (though probably incorrect) explanation we get from Mexicans of the origin of the word is that it came out of the Mexican-American War. The story goes that the American soldiers were wearing green uniforms. The Mexicans would overhear the American commanders yelling, “Green, go! Green, go!”, hence the term ‘gringo’.
In Oaxaca, only a few people call us gringos. Many people are afraid that we think the term is offensive (and apparently some Americans are offended by it, though I’m not sure why), so we often get a chuckle or a surprised response when we use ‘gringos’ to refer to ourselves.
The term most commonly used to refer to white people around here is ‘güero’, (which is pronounced more or less WHERE-oh).