Well, this is a tricky one. My native language is northern - midwestern American English.
Having live in the UK and Scotland for 16 years, I have been forced to learn many UK / Scottish words in order to be understood. I now hoover, buy courgettes, put my messages in the boot, and frequently have a blather in the playground with the other mums unless it is a cold dreich day when we stand in the bike shed.
I haven't however lost my American accent (although friends and family in the US would disagree).
When I first moved here I experienced numerous embarrassing moments:
A much younger me to a Welsh rugby fan in a Scottish pub: 'I love your
pants!' The Welshman, very helpfully, stood up and began to unzip in order to show me! Me:
After an evening out with a prospective boyfreind the young man says 'Right, I'll come round and
knock you up about about 9 o'clock tomorrow'. 'You'll
what!!'
I love English!