"Bonjour madame, 363 grammes de ce fromage-la, s'il vous plait."
An elementary request; if I wanted 364 grammes, or 362, I'd ask for 364 grammes, or 362.
"Quoi, pile?" [Luckily I knew that "pile" here means "exactly".]
"Oui, pourquoi pas?"
"Sortez, sortez maintenant!"
A communication failure. In particular, I've not conveyed the fear and confusion that flickered across Madame's face just before she threw me out. That made the encounter a win.