Back Door is a form of malicious feature in which the program is configured to respond to commands sent to it from the developer. A Universal Back Door is an ability of the developer to remotely change the program to do anything the developer desires it to do. Sometimes Universal Back Doors are called "Auto-Update".
This comment thread is for people to document various implementations of this malicious feature.
I decided to re-watch the first Transformers film today, but differently. Instead of indulging in it as mindless entertainment, I decided I want to actually view it seriously, as I would with somebody like Steven Spielberg, who, by the way, was an executive producer on the film.