Three old sisters 92, 94, and 96 years old, respectively all lived together.

One day the oldest drew a bath. She put one foot in the water, paused, then called downstairs to her sisters, "Am I getting in the tub or out of the tub?"

The middle sister started up the stairs to help, then paused and called back downstairs, "Was I going up or coming down?"

The youngest sister, who was sitting at the kitchen table having tea, said, "I guess I'll have to help. I hope I never get that forgetful!" and knocked on wood.

She got up then, paused, and called, "I'll come up as soon as I see who's at the door!"