Appreciating metaphors can help children appreciate the beauty and power of language. Have some fun with this, over time. Create a little ritual (high fives, keeping score, etc.) when you spot one. Keep a list on the refrigerator.
Here are a few familiar metaphors.
His head was spinning; feel blue; broken heart; apple of my eye; a moving speech; heated debate; deep thoughts; breaking news; winds of change; glued to their seats; end on a sour note.