So, my #1 son, 19, was in the hospital for surgery. (Nothing life threatening, but one of those Must Be Done things).
He's coming out of general anesthesia, still woozy, and the nurse is explaining the patient-controlled morphine thing. So there he is, half conscious, absolutely _grilling_ the nurse over whether the ten-minute timeout on the thing is ten minutes after the last time the button is pressed, or does the gate open at 11:10, 11:20, etc.
All complicated by the fact that it took the nurse several tries to understand that he wasn't anxious about getting his meds -- he just had to understand how the thing _worked_.
And "let it go, son" doesn't work well when he's fully awake -- there's no hope of it working when he's in that state.
Finally, he fell asleep. We were all relieved.
Needless to say, he's entering an engineering program this fall.