When there is a twist in a movie that has no build up, makes no sense and happens just to shock the audience.
Such a practice was created by Rian Johnson with his controversial movie, The Last Jedi.
Guy 1: Hey dude! Did you see that movie?
Guy 2: I did, and it was shit.
Guy 1: How so?
Guy 2: The characters are bland, and the movie does the Rian-Subversion too much.
Guy 1: Dear god...