Evidence I don't eat right

I've had an apparently permanent pimple or other blemish on my forehead for as long as I can remember. Mom asked about it during breakfast.

A.: So if we leave within an hour...
Mom: What's that on your forehead?
A.: What's what on my forehead?
Mom: That?
A.: It's a pimple.
Mom: Huh.

Later

Mom: What's going on with your skin?
A.: Nothing?
Mom: You have that spot on your forehead.
A.: I've always had that spot on my forehead.
Mom: No, you haven't. It's evidence that you don't eat right.