Three old ladies were sitting around talking.

One said, “Sometimes I catch myself with a jar of mayonnaise in my hand in front of the refrigerator and can’t remember whether I need to put it away, or start making a sandwich.”

The second lady chimed in, “Yes, sometimes I find myself on the landing of the stairs and can’t remember whether I was on my way up or on my way down.”

The third one responded, “Well, I’m glad I don’t have that problem, knock on wood,” as she rapped her knuckles on the table. Then she told them, “That must be the door, I’ll get it!”