Three Blondes

There were three blondes living together. Blonde #1 was coming back from grocery shopping, and she dropped her keys. She walked down the stairs to get them, and she said to herself, ''Am I going up the stairs or down the stairs?'' So, she stood there puzzled, the bags of groceries still in her hands.
Blonde #2 was taking a bath, and was draining the tub because it was too cold. With her hair still dry, she said to herself, ''Was I getting in the tub or out of the tub?'' She stood there, just thinking about it.

Blonde #3 was sitting in the living room in front of the coffee table, and she said to herself, ''Knock on wood I'm not as stupid as the other two!'' She knocked the table. ''Was that the front door or the back door?''