César lets out a sharp laugh at the correction. Look, it's funny. He can picture the rage perfectly. The rest, he listens to eagerly, truly curious about her professions.

When she gestures to the forge, César turns and looks at it, whistling in appreciation. "Explains why it's so hot in here."

The joke is a two-fold one. He's not saying the thing everyone would say, but making fun of the thing everyone would say. All in the tone.