Once in late pregnancy, your honour I asked someone to be quiet in a normal carriage. It was late commuter train where everyone is a bit knackered and grumpy and I'm not sure he wasn't actually on drugs because he was chatting nineteen to the dozen to someone making non-committal noises back. I was sitting between them in the aisle.
Actually I think my exact words were "OH MY GOD DO YOU EVER SHUT UP?! TAKE A BREATH MAYBE?"
He sort of spluttered, then made a phone call, during which he told the person on the other end of the line that he'd have to be quick because someone thought he was being loud.
"YES YOU ARE," I added loudly. He hung up.
The rest of the carriage was silent - could have heard a pin drop silent.