One of the guys on my Gnat course went into a shop in Llangefni or somewhere. The locals immediately switched to Welsh and made some rude comments....
Mistake. Said chum was a fluent Welsh speaker from South Wales, who gave them his robust opinion of ignorant locals who went out of their way to be rude to vistors!
It was quite amusing listening to the locals jabbering away in their local language. Every few moments an English word would be needed for inventions new to them, such as 'fire' or 'wheel'....