Eat Pray Love.
The two women have just discussed eating, muffin-tops, body image, etc, and Julia Roberts says to enjoy the pizza and just buy bigger jeans.
So in the next scene they are buying jeans, but doing that stereotypical-joke thing of lying on the changing room floor trying to pull up the zip on too-tight jeans.
Why? - that totally defeats the object.
I guess the male writer/director thought it would be a fun scene, that is how he imagines women always shop for jeans.
It just makes no sense in the context of the film.
What scenes really annoy you?