Three elderly sisters are sitting in the living room, chatting about various things. One sister says, “You know, I’m getting really forgetful. This morning, I was standing at the top of the stairs, and I couldn’t remember whether I had just come up or was about to go down.”

The second sister says, “You think that’s bad? The other day, I was sitting on the edge of my bed, and I couldn’t remember whether I
was going to bed or had just woken up!”

The third sister smiles smugly. “Well, my memory’s just as good as it’s always been, knock on wood.” She raps on the table. “You sit still. I’ll answer the door.”