A plot device or plot mechanism[1] is any technique in a narrative used to move the plot forward.[2] A clichéd plot device may annoy the reader and a contrived or arbitrary device may confuse the reader, causing a loss of the suspension of disbelief. However, a well-crafted plot device, or one that emerges naturally from the setting or characters of the story, may be entirely accepted, or may even be unnoticed by the audience.
It's rather like the message on this common sign which is literally out of the blue:
In related news and timing, the release date set for "Cosmo" Kramer's autobiography is June 4th, Iyar 27 which is the ALT "everyone out of the box" date in the narrative of the Great Flood (27th day of the 2nd month).
(The word "ark" for Noah's ark and also for Moses' floating bassinette is a teiva, lit. "box". An acronym is called a "roshei teivot" for the "heads" of "words" which again, are "boxes.")
All the world's a stage,
And all the men and women merely Players;
They have their exits and their entrances,
And one man in his time plays many parts,
His Acts being seven ages. At first, the infant...