I was once at a restaurant beside a girl and her parents and a friend of the parents. All were American, but the girl, who had just returned from spending one semester at a university in England, spoke with a strong RP accent. Similarly I met someone (who was starting graduate school) from Texas who had just spent a summer in Germany, and spoke with an exaggerated German accent. I don't understand how they didn't realise that it made them seem foolish, rather than, as they seemed to hope, interesting and sophisticated.