Miles and Vivienne are just starting to pick up on figures of speech. For example, I said something about "running errands" a month or so ago. Vivienne asked me when we were going to start running. Last week, I mentioned something about how they had "worn" a toy "out". Vivienne said, "We don't wear that!"
It's interesting to see how literally they take something that I say to them. This is just the another step in learning all the many nuances to the English language.