Alzheimsers joke

An alzheimser sufferer was looking at some pieces of moss that had fallen from his roof recently.
His visitor noticed that some birds were picking at the moss.

He said to patient 'why would they be picking at the moss he responded
there might be worms in it.

Visitor said how would worms get up on the roof.

Responded there is a ladder out the back?

Man, but that must be one of the worst ever, take a bow and keep the rest to yourself.