Vegetable Brain?

I managed to get Karina to sit down and do some studying without fuss or distractions yesterday and today. We sat down and did some English, some Maths and also learned how to tell time. All because of an out of the blue comment I made. As usual, Karina would be a little hesitant when I mention that it's "school" time. She would rather be playing.

Mommy: If you don't do your work, you will end up with a vegetable brain.
Karina: What is a vegetable brain?
Mommy: You know like a rotten vegetable? What do we do with rotten vegetables?
Karina: Throw away.
Mommy: Yup, that's right. If you don't exercise your brain, it will end up like a rotten vegetable.
Karina: Hahahaha. Mommy, that is so funny.

(While doing work)
Karina: See mom, I'm exercising my brain.