Seizing a "teaching moment" I said, "That 'fire thing' is called a fire extinguisher. The word extinguisher means it can be used to 'extinguish' or put out a fire. Can you say extinguisher?"
Ellie smiled and pronounced it beautifully.
So I turned to Mila and said, "Can you say extinguisher?" She replied, obviously somewhat miffed at the question, "Of course I can. It's English, isn't it?"