Re: English native speaker here.
When I was a kid, I used to go on holiday with my parents and stay in a little village on the Lleyn peninsula. One day we were in the local shop, and one of the locals was yakking away in Welsh to the shopkeeper. I don't know what they were saying, but my mother suddenly gave them a mouthful in Welsh, much to their surprise. I later asked Mum what that was all about, and she said that they were being rude about "Saesneg" (foreigners) overrunning the country and blocking the roads with their cars. Apparently, my mother had been stationed at a nearby NAAFI Rest and Rehabilitation facility during the war, had been billeted on a local farm, and had learnt Welsh in order to integrate better with those same locals.