Three old ladies were sitting at the dinner table discussing

 their problems with getting old. The first one said, “Sometimes

 I catch myself with a jar of mayonnaise in my hand, while

 standing in front of the refrigerator, and I can’t remember

 whether I need to put it away, or start making a sandwich.”

The second lady says, “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 says, ” Well, ladies, I’m glad I don’t have any of

 those problems, knock on wood.” As she hit her knuckles on

 the table she looked up and said, “That must be the door… I’ll

 get it!”