Three old sisters

Three sisters, ages 92, 94 and 96, live in a house together. One night the 96-year-old draws a bath. She puts her foot in and pauses. She yells to the other sisters, "Was I getting in or out of the bath?"
The 94-year-old yells back, "I don't know. I'll come up and see." She starts up the stairs and pauses "Was I going up the stairs or down?"
The 92-year-old is sitting at the kitchen table having tea listening to her sisters. She shakes her head and says, "I sure hope I never get that forgetful, knock on wood." She then yells, "I'll come up and help both of you as soon as I see who's at the door."