How Much Did You Hear?

Gandalf: What did you hear?! Speak!
Sam: N-nothing important! That is, a great deal about a ring and a Dark Lord, and something about the end of the world...

—The Lord of the Rings

Alice and Bob are speaking to each other, and Alice tells something to Bob in confidence, only intending for it to be heard by Bob.

As she says it, Eve, a third party who may or may not be the topic of discussion, walks up behind Alice, within earshot.

Alice realizes that someone's behind her, sometimes when she sees Bob trying not to panic. Alice turns around and, red-faced, asks "Er... how long have you been standing there?"

This also works in more serious settings, where Alice is a villain. She blabs her evil intentions. Eve, the hero, responds: "Long enough for me to know what you're up to!" or the like.

In both scenarios, Bob is superfluous, as Alice can simply be just muttering to herself.

Examples of How Much Did You Hear? include:

Anime and Manga

In Cowboy Bebop, Faye's conversation with Ein about her past life is overheard by Spike from a nearby bathroom.

Faye: How long were you in there listening?
Spike: Too long. Your story needs editing.

In the English dub of Ranma ½ after Ranma defuses Ukyou's vengeful wrath by observing that she's cute.

Akane: Ahem!
Ranma: How much did you hear?

Fan Works

Played with in Kyon: Big Damn Hero. Kyon discovers his sister eavesdropping Haruhi when she's outlining Mikuru the base of her plan for a type 2 Tenchi Solution. While Tsuruya wonders what she overheard, Haruhi doesn't really care about how much exactly she knows: she just cares that she doesn't tell anybody else.

Film

Employed for a glurgescent moment in The Goonies, wherein the rest of the gang enter during Mikey's heart-to-ribcage talk with a very dead pirate.
Was done well in the movie The Fellowship of the Ring (see the quotation above).
- And in the books too, naturally.
- Failed in Bakshi's animated abomination, where Sam adds "And elves, sir!"... even though elves were never mentioned.
  - In all fairness, though, Bakshi's representation of Sam fell somewhere between Cloudcuckoolander and The Ditz.
  - ...or because Sam's line was pulled unmodified from the book, where Gandalf does mention the Elves...
Tom Hanks' son overhears Hanks talking about his college conquests in Sleepless in Seattle.

Sam: What did you just hear me say?
Jonah: (defiant) Six girls in college, maybe seven!
Sam: Seven. EIGHT! Mary Kelly!

Double Indemnity: As he is finishing his recorded confession of murder, Neff looks behind him to see Keyes standing in the doorway.

Neff: How long you been standing there?
Keyes: Long enough.

Spaceballs:

Dark Helmet: Did you see anything?
Colonel Sandurz: No, sir! I didn't see you playing with your dolls again!

Literature

In Astrid Lindgren's The Brothers Lionheart, this happens to Karl Lionheart. He overhears some of the bad guys talking at their campfire, while hiding in a cave. In reality he can hear quite a lot. When they find him the next morning, he claims to have slept all night and not heard anything. "You can't be serious", says one of the bad guys, "have you really not heard anything of our partying and singing last night?" Karl squirms: "Well, maybe I sorta heard you sing a bit" - and they release him to (what they think is) his home.
Variation in The Lion, the Witch and the Wardrobe: After getting a big lesson on the situation in Narnia from Mr Beaver, the Pevensie children suddenly realize that Edmund is missing. The whole party then tries to remember how much he has heard, and thus will be telling to the Witch...

Live Action TV

In the Firefly episode "Heart of Gold," Inara engages in a confidential conversation with an associate of hers, and right after she gets finished, she looks up and sighs, facing away from the door to her shuttle.

Inara: "I suppose you heard all of that?"
Malcolm Reynolds: (leans in through the door) "Only 'cause I was eavesdropping."

Doctor Who had a variation of this in The Power of the Daleks, where a character overhears the Big Bad telling a colleague that said character has to be killed. What he doesn't know is that the Big Bad has his colleague more or less at gunpoint.
In an episode of The Nanny, Max is talking to Fran about something confidential. When he's done he presses the intercom button and asks "Your big fat ears catch all that Niles?"
- It's a running joke that Niles knows about everything going on in the house long before any one else does by eavesdropping.
In an episode of Community, Abed, in an attempt to mess with Troy's head, is pretending to be an undercover alien. At one point he pretends to send transmissions while hiding behind a bush Troy is sure to walk past. When Troy comes by and overhears him, Abed asks "how long have you been standing there?" to further the illusion that he's hiding something.
In How I Met Your Mother, Robin catches Ted playing with his model of the Empire State Building.

Robin: Were you reenacting the last scene of Sleepless in Seattle?
Ted: How long have you been standing there?
Robin: Ten seconds.
Ted: Then yeah, just the last scene.

In a first season episode of The Closer, an arrogant entitled rich kid had murdered his parents Mexican maid's daughter, and then fled to Mexico where the LAPD had no jurisdiction, taunting Brenda with his intention to vacation there permanently. Brenda requests that the Mexican authorities arrest him prior to an extradition process, and then visits him, during which time Brenda threatens to arrest his parents for the crime, listing all of the circumstantial evidence which could be made to point to his mother and his father's complicity after the fact in arranging the kid's escape to Mexico. The kid agrees to a full confession if Brenda agrees not to prosecute his parents. Brenda then announces that while she had no authority to arrest him, the Mexican police officers standing behind her were fully fluent in English and had just heard him confess to killing a Mexican citizen, do have the authority to arrest him, and that the Mexican prisons and prisoners were probably going to be a whole lot worse for him than the American version.

Video Games

One of Shepard's lines to Joker after the latter interrupted an Almost Kiss in Mass Effect is "Are you spying on us, Joker?"
Happens between Ratchet, Captain Qwark, and a monkey in Ratchet and Clank Up Your Arsenal.

Qwark: [to Skrunch the Monkey] It was mating season. How was I to know she was your sister? [Notices a squicked out Ratchet and Clank standing behind him] How long have you been there?
Clank: Too long.

Said in the RPG Golden Sun at the beginning of the game, after the Heroic Mime overhears the Knight Templars' plans to steal the MacGuffin of the game. It does not go well for him.
One Private Action in Star Ocean the Second Story involves Claude or Rena overhearing Celine fretting in her room at the inn. Getting too close to the door causes them to trip (and reveals to the player just what she was worrying about), drawing her outside. She immediately asks if they overheard her, and they can choose to deny hearing anything or try and comfort her. (The best course of action is to walk away before you get too close and trip, as she reacts negatively to both possibilties.)

Web Comics

Used, Lampshaded, subverted, and inverted in the Sprite Comic Bob and George. Dr. Wily was the usual victim.
- Also Dr. Light denies -- and asks George what he saw.
Done twice in the Web Comic Dominic Deegan: Oracle for Hire. Both times, "Bob" was Dominic and "Chet" was Siegfried.
In Order of the Stick, Hinjo confronts Shojo after hearing him talking to Roy about how they're working behind the Sapphire Guard's back and violating Soon Kim's noninterference oath, asking "Have you been lying to us?" Shojo says his answer "all depends... on how much you just overheard."
Lampshaded straightforwardly in this Multiplex strip.
The Inexplicable Adventures of Bob. Bob overhears Fructose Riboflavin muttering to himself about his tragic, secret motivation for everything he's done. Bob offers a word of sympathy. Riboflavin realizes Bob has been standing there, shouts, "That was not meant for your ears!" and launches himself at Bob. And crashes into a wall. It's dark, you see.

Web Original

More of "What did you see?", but in Darwin's Soldiers Shelton almost asks this after Agito implies he witnessed Shelton and Shakila upgrading their relationship in the closet.

Western Animation

One episode of Jackie Chan Adventures had a story to the West where the character Jade represented overheard Valmont's ancestor's plans. She averts the usual villainous capture by speaking in Chinese. The bad guys assume she doesn't understand a word of English and lets her go. Too bad she does.
An episode of Transformers Prime had Knockout overhear Starscream taunting Megatron's lifeless corpse, bragging about how he killed him. Of course, since Knockout has been helping Starscream against Megatron he suffers no punishment.