Three older ladies were discussing the travails of getting older.

  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, some times 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 told them "That must be the door, I'll get it!"