Yeah, dementia's a cruel thing....My 93 y/o grandfather went to the doctor complaing that he was losing his faculties. The doc checked him over and he seemed to be in perfect health for his age, so asked grandad why he thought that...
"Well it's like this you see, I saw the missus naked on the bed and I asked her for a quickie.'
"And what did she say to that?"
"She told me:"Get out of it you dirty old bugger, you've just had one.""