Little Did I Know

Uttered by the main Narrator to the audience, to indicate that a major plot is about to happen.

"I was just an Ordinary High School Student, that normal, peaceful day. Little Did I Know that this was all going to change." or "I thought it was over. Little Did I Know, it had only just begun."

This line probably originated in 19th Century English romance/gothic novels. The heroine innocently takes a "position" or visits some place where evil lurks or adventure looms behind a calm, civilized veneer She begins the narrative of the novel, with classic British understatement, something like this: "If I had but known that I would soon be facing a madman with an axe in those dank catacombs, I would never have had the courage to get on the train to Sussex that fatal day last summer . . ."

Related to How We Got Here if it gives away unlikely-sounding details of the plot ahead of time. Found only in first-person narration and omniscient narration with a chatty narrator. Since it's basically a way to invoke Foreshadowing without any actual, you know, foreshadowing, it's a Discredited Trope.

Examples of Little Did I Know include:

Film

The movie Stranger Than Fiction, in many ways a movie about stories and tropes, features a literature professor who explains that he's taught "entire seminars on 'little did he know.'"
Appears in the Opening Scroll of Return of the Jedi, regarding Luke not knowing about the construction of the second Death Star.

Literature

There are about two or three of these, played absolutely straight, per Dresden Files novel.
Ciaphas Cain is prone to using this at the end of chapters.
- He loves to describe how "if only he knew" what fantastically lethal enemy awaited him, he would freeze/run away as fast as possible, and frak whoever's around/just shoot the character about to get him in trouble, while proceeding to do the exact opposite. Even Amberley isn't sure how serious he is sometimes.
Derided in the Ogden Nash poem "Don't Guess, Let Me Tell You."
In Angels & Demons, when Robert Langdon hears in passing a factoid about how a reasonably small piece of cloth can significantly reduce an object's falling speed, he remarks (in narration) that he didn't then realize this information would later save his life. The payoff doesn't come 'til near the end of the book, when the reader has probably forgotten it.

Live Action Television

The Goon Show has used this for comedic effect.

Seagoon: (after two other characters have made asides to the audience) Little do they know how little I know about the little that they know. If only I knew the little they know about the little that I know, then I'd know a little. I'll have to keep my little ears open, you know.

Video Games

Gothic:

Another convict was brought to the cliff. He did not know, but he would change everything.

Western Animation

An episode of Darkwing Duck that took place in Medieval times subverts this. Darkwing's public persona was working in the royal castle. After watching the King and Queen acting like fools, he turns to the camera and says, "Little do they know... And I do mean little."