On Maersk Air, sometime back in the 1990s, LGW/CPH. It's all going smoothly as we prepare to go flying, and we get to the safety demo.
Cabin PA in English: "We will now do the safety demonstration in Danish only."
Cabin PA in Danish saying the same thing, followed by a safety demo in Danish only. Some of the obviously British passengers looked quite put out
My Danish relatives all thought this was extremely funny when I told them about it.