many years ago on an F27 in oz, nsw. just finished shutting down l/h engine the capt called crew over interphone to " get the passengers off now" . hearing the tone in his voice the cabin crew did exactly that. they then reported to capt still on the deck "cabin evacuated". that really got his attention. what he had meant to tell the cc was a heavy storm was about to hit tha a/p and he didn't want anyone getting wet!
it's always about communication