My family are from North London originally, so I do find myself going full on London mode when I'm around Londoners. I'm even ashamed to say I sometimes throw my own cockney rhyming slang in conversations without realising. I once told someone that something cost me a Caitlyn Jenner, which earned me a completely baffled look...

It's funny how that works. I do that with Thai people now; a lot of the words are the same in English but you have to pronunciate every syllable and the tones are all over the place.
For example: SA-tor-ber-EEE!

I love that little anecdote, it genuinely made me smile. I once got an English friend of mine when we were drunk to say to the Italian receptionist at the hotel in Italian, "I want to buy your children, how much is the boy?"