This recorded announcement came over the speaker on our SwissAir flight ZRH-VIE a few days ago:
Further to the Captain's announcement, stay calm. Remove ties, collars, and sharp objects.
At that point a flight attendant walked very quickly toward the front of the plane.
Fortunately we were still parked at the gate at ZRH and it appears that somebody had pushed the wrong button. We have to admit that it did get our attention.
We hope never to hear that announcement except by mistake.