My daughter, in her normal speech, is very decidedly central Iowa English (yes, there is such a thing), but she does have an ear for languages, dialects and accents. For an absolutely obvious white girl's (German and Scandinavian on my side or the family, pure Scandinavian on her mother's side) appearance, she can spontaneously come out in perfect Ebonic speech. Also, after 3 years of high school German, she got to go over as a foreign exchange student to Germany in her senior year. Her German was good enough that while native speakers could tell she was not a native speaker, they had no clue that she was American, putting her as Dutch or Polish most of the time.

Later, when she was working at a local McDonald's she used to freak out customers. One of her co-workers was from Costa Rica, but had spent a good many years in Germany, for some reason or the other. My daughter had also taken Spanish when she had exhausted all the German courses in high school and picked it up almost as well as German. So customers would see/hear here talking in German to the to the girl at the counter, then yell back to Mexicans in the back in Spanish and then take the customer's order in central Iowa English.