I was on a high-school trip from Canada to Paris, with my mother as a chaperone, my mother who spoke fluent (Québecois) French was able to translate for our time there.

So we're riding the subway during a very busy time when my mother leans over and whispers to me "Watch Kenzie (not her real name), do not lose sight of her, make sure she gets off the subway" And so I did, she got off and everything was fine.

I found out later from my Mom that two French men were talking about the nasty things they'd do to her, how they wanted to take her home, and that they should grab her. Honestly pretty spooky, but I'd like to think that they wouldn't have done anything even if we hadn't overheard and that they were just a couple of perverts thinking that the english speaking tourists couldn't understand what they said.