Mothers have eyes in the back of their heads. They may not show up on X-rays, but they're there.
Like a lot of youngsters, I used to get my mother to turn her head so I could search through her hair for the eyeballs she claimed to have back there, telling her, "No you don't! No you don't!" But when I'd scamper off to another part of the apartment and pick up an ashtray or fiddle with the window blinds, I'd hear my mother's voice ring out, "I can see you! I know what you're up to!"