Susan and Sharon are in their cabin talking about divorce and their ages, among other things.
At the beginning of this scene, Susan's bed is made-up with the head at the right-hand end. She picks up the pillow, puts it at the foot of the bed and lays down on it.
Susan says; "Pretty soon there'll be more divorces than marriages", to which Sharon replies; "Is it the truth"?
The next shot shows Susan lying on the bed with her head at the foot of the bed (the left-hand end) which is now made-up to be the head! She says; "I can't wait till I'm eighteen and get my own car and stay out dancing till midnight".
This condition remains until after Susan says; "No kiddin', that's my birthday too"! when the bed is made-up as before with the head at the right-hand end!
A video of the film.