Malcolm: What's wrong with him?
Lois: The doctors called it "hysterical conversion disorder." It's psychosomatic. Apparently, he's paralyzed from the waist up.
Malcolm: Waist up?
[Hal shakes in his chair]
Reese: Dad, what is it?
[After Lois scratches Hal's nose, Hal's foot rubs up against Lois's leg]
Dewey: I think he's thanking you.