Start by naming any country that France borders. Then name any country that borders any of those countries. Then keep going until there are no more countries left to name.
It's what Symmetra used to say when she had put her shields on all allies, now I think it's an alternate line for when she uses her shield generator ultimate. I didn't even pick it to be a trick question; I was just looking for something that sounded in-character for her without being as obvious as "teleporter online."
Thanks! There are one or two that are unintentionally tricky, like the defensive matrix one for Symmetra, but I tried to choose a lot of lines you hear frequently while playing.