There is a logical reason for this. Well, logical for Deadpool
Um, this isn't what it might appear to be. Anastasia Luccio: Madre di Dio
, Harry. I cannot for the life of me imagine what it does
appear to be.
Whenever you try to explain a storyline to a friend, especially in Arc heavy shows, you often have to pepper your dialogue with a "Not Making This Up" Disclaimer.
When you watch a story from the beginning, when a major plot point happens you are often primed for it because of the events of the story that build to it. Then you try to explain it to your friends... which results in blank stares, because they weren't primed the whole story for it, no matter how well you describe it to them.
This is a phrase to use when describing a complicated story point, because really, a person does not need to hear the history of Star Trek from the beginning to understand the use of a trope.
The reasons why this is needed can vary, quite often due to Continuity Lock-Out, Mind Screw, and/or a Kudzu Plot.
See also Less Disturbing in Context, a closely related concept, and Makes Just as Much Sense in Context, the direct opposite of this. May be lampshaded by calling a statement A Rare Sentence.
As this is a page defining fanspeak, there's no need for examples, though obviously this can happen in Real Life as well due to lack of context.