The traditional view of theater is that three walls surround the actors (or "players" as they are sometimes called) while an invisible "fourth wall" separates the characters from the audience.
There is also the notion of a "fifth wall" that represents either the very real dissonance between theatrical practitioners and scholars, or the imaginary barrier between individual audience members during a shared viewing experience.
Enter stage left Brad Pitt.
"Were it not for this wall beneath my feet," said Pitt, pointing to the 'floor', "I would be unconstrained in my craft as an actor. My intention is to break through this wall." Proceeding to kneel while producing a set of crude tools that could in theory allow him to 'tear down the wall', Mr. Pitt began the task.
At last check the famous actor was still working on his new project in earnest, while his famous actress partner was still batshit crazy as well.