On the way to the park today.
Christy: "We need to water the garden when we get home."
Lucy: "Why do plants need water?"
Christy: "Plants use water to cool themselves and to move food through their bodies."
Lucy: "And then they poop?"
Christy: "No, plants don't poop."
Lucy: "When people eat then poop comes out of their butt."
Christy: "Yep. That's pretty much it..."