No I don't find that offensive... But being married to a Canadian and being called a "Yank" or "Yankee" on occasion (I know this is popular with Canucks, Brits, and Aussies), this one you have to watch out for calling people from the south. If they have a southern or "hick" accent beware. Yank is a derogatory term southerners use to refer to northerners in the states. 'murica is definitely a hick term but I think most of us can take a joke.