We all know about method actors. Are method writers a thing? Because according to an unnamed insider of unknown origin and access, Ben Affleck would rewrite portions of the Batman v Superman script while wearing full Dark Knight regalia. From US Weekly:
The Oscar-winning screenwriter "would go into wardrobe and get all suited up for the day in his Batman suit", explains the insider of the action flick. "Then he would sit around reworking the script. Ben wasn't thrilled with it and would find himself on multiple occasions fixing it the day of."
While it's worth noting that Affleck was tinkering with the Batman v Superman script even into shooting the film, it's really not that unusual. And sadly, this probably wasn't Affleck getting into his costume just to feel "Batman-y enough" to write his dialogue; it's much more likely that Affleck had to get the cape and cowl on for the day's shooting, had a bunch of downtime between takes, and used that time constructively by punching up the script.
That said, I have a glorious image in my head of Affleck renting a hotel room, bringing his Batman costume and his MacBook Pro, and then screaming at Microsoft Word for a week until the film met his standards. "'Clippy! CLIPPY! DO YOU BLEED?! You will.' Hey, that's pretty good."