A person who watches nothing but Marvel movies, specifically those from the MCU, and thus only expresses real life events and their taste in film relative to bland, boring, formulaic CGI-fests. Usually over-sensitive to spoilers and thinks Scorsese films are overrated, but hasn’t seen any.
CAPESHITTER: “Bro, have you seen that new Deadpoolmovie? It’s epic, like bacon!”
A superhero movie where the hero is merely there to show off their superpower, rather than doing heroic acts people can actually relate to, they simply show off the cool tricks they can do to the screen. Going off of the saying "not all heroes wear capes" it's called capeshit because only the (metaphorical) cape has been cared about in the production of the movie.