Does anyone know why the doc says "TURN YOUR HEAD" and cough???answer to come later!(I'm a registered nurse)
I'm guessing it's for two reasons: as mentioned above, so you don't cough on the doctor, but more importantly - it tricks some parts of the nervous system to prevent them from "compensating."
My neurologist had me seated on the exam table, and was checking my reflexes. He did the little "hammer-on-the-knee" thing, and repeatedly got no response. He then said, "hold your hands out in front of you, lock your fingers together like so, and pull apart..." and then tapped on my knee again. He got a response. He explained that the brain "compensates" sometimes, and if you distract it, you get a better clinical view.
Of course, both of those are probably wrong. It's probably so that he can stare at your goods without you seeing him staring.