squarehead

Squarehead is a late 19th century ethnic slur directed at German and Scandinavian immigrants. The phrase is meant quite literally as a disparaging reference to the cranial features, though often just used as a generic ethnic slur against those groups. Basically the stereotypical shape of a Northern European's head was thought to be square- so it was (and is) an insult to call someone with that ethnic makeup squarehead.