I can think of several things I ought to try this for!

It reminded me of when DS was 2 or less, and he went out on the balcony to play in the rain. I was sitting there thinking, well, he'll come in if he gets cold, and suddenly it occurred to me that he didn't know that coming inside would solve being cold. Sure enough, he was sitting outside in the rain, shivering and crying. I felt so bad, but it was a good lesson in what rules might not be innately understood.