Brain Pain

Little Zed, who is almost 4, keeps me on my toes. The stuff that comes out of his mouth causes me to stifle giggles or my jaw to drop, each and every day.
Today, he told me, while tapping his temple, that his mind just wasn't working properly. I tried to pry some more information from him, but he just repeated that his brain wasn't working properly.

I have been perplexed ever since. What DID he mean by that?!