Knock on Wood Joke

Three sisters ages 72, 74, and 76 live in a house together.

One night the 76 year old draws a bath. She puts her foot in and pauses. She yells down the stairs "was I getting in or out of the bath?"

The 74 year old yells back "I don't know. I'll come up and see." She starts up the stairs and pauses. Then she yells "was I going up the stairs or down?"

The 72 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." She knocks on wood for good measure.

She then yells "I'll come up and help both of you as soon as I see who's at the door".