Okay, the ambulance story reminded me of another one...
We used to carry Braille books for the safety demonstration on board the aircraft, obviously to be offered to blind passengers. Just after making one of my flight crew aware that we had a DEAF passenger on board, she let me know she had verbally briefed him and given him the Braille book!
When I walked back to the passenger (who hadn't heard a word she said,) he was just sitting there with this huge book in his lap, looking at it...