Let's say you meet someone whose English is so good that you can't tell where they're from. If they're old enough to remember 1986, just say one word: Falco. Most people will just say "the Amadeus guy?" But anyone from Austria or Germany will immediately begin loudly singing the chorus to "Jeanny". And now you can pretend that you recognized their accent, and can tell that their native language is German.
Here's a silly party trick:
Let's say you meet someone whose English is so good that you can't tell where they're from. If they're old enough to remember 1986, just say one word: Falco. Most people will just say "the Amadeus guy?" But anyone from Austria or Germany will immediately begin loudly singing the chorus to "Jeanny". And now you can pretend that you recognized their accent, and can tell that their native language is German.