I saw a patient today who kept making odd comments in response to my questions. His wife ended up answering for him most of the time. I assumed that he was just deaf, but as we left the room he said, "Goodnight!" in a cheery voice. It was 10.30 in the morning.
So I said to the GP who was there, "Does he have a bit of dementia?"
"Oh yes", said the GP, "He's as nutty as a fruitcake".