A character wants to talk about another behind their back but is in the same room with them. He assumes the pose of silence. Leaning forward in a conspiratorial manner, rendering everything said perfectly inaudible to the other, even if only a few feet away in an otherwise silent room.
Stage Whispers, where the asides and "private" discussions are held in full voice (loud enough for the audience to hear, obviously) but other characters freeze or act as if they hadn't heard it, are an established dramatic convention in live theatre. A similar convention surrounds soliloquies, where one character makes a speech to the audience but is unheard by any other characters on stage. Albeit, truth be told, this is not that trope, you're wanting Thinking Out Loud. These conventions are Older Than Steam, dating back at least to William Shakespeare.
In written media, it's usually described as someone 'leaning in a conspiratorial manner' or something similar.
If neither the audience nor characters other than the intended target can hear what's being said, then it's a Silent Whisper. Compare Overt Rendezvous, when the characters share sensitive information in public spaces with no one being the wiser. A Room Shuffle can be arranged, to dodge this trope and provide a little action. This is sort of the inverse of a Silent Conversation, when regardless of volume, the audience can't hear what the characters are saying but eavesdropping characters might.
Examples:
Anime & Manga
- The Mermaid Princess's Guilty Meal: Ela reveals herself as having having a palate for fishpeople in a conspiratorial whisper to Gill-chan. Subverted because everyone else hears her asking how one of his sergeants tastes.
Arts
- Marriage A-la-Mode: In "The Marriage Settlement", the soon-to-be-married couple is sitting on the same, rather small couch on the far right. The bride is sighing unhappily as she is courted by an Amoral Attorney. Both are leaning toward each other while the groom has his back turned to the bride and is vainly admiring his own reflection.
Comic Strips
- Garfield: In two separate strips, a waiter at a coffee shop has leaned toward Jon while covering his mouth with his palm to tell him that Jon's girlfriend (actually Garfield) oughts to shave without no one else being the wiser. Of course, since Garfield is a cat and has finer hearing than humans, is perfectly able to hear him.
Fan Works
- The Moonstone Cup: Twilight becomes so much of an in-universe Memetic Badass that people excitedly whisper about her. One Gryphon, who hilariously fails to recognize it's Twilight to whom she's talking, lowers her voice and leans her head down to divulge the wild rumor of Twilight being Celestia and Luna's sister.
- Promises of a Wandering Hero: Shirou barging in to save the day is commented on by Tsuruko who closes ranks with Motoko and tells her that sometimes heroes show up at the last possible moment. Of course, given everyone else's eyes are trained on Shirou, they aren't heard at all.
- The Rigel Black Chronicles: In "The Ambiguous Artifice", Fred and George, being their usual melodramatic selves, adopt a conspiratorial tone when they reveal why their mother doesn't want them in her kitchen—they once blew up her favorite cauldron as a prank.
Films — Live-Action
- The Godfather: Don Vito is at the receiving end of this whenever one of his Consiglieres wants to report sensitive information to him while in the middle of a meeting with subordinates or other crime bosses.
- Harry Potter and the Chamber of Secrets: Harry, Ron, and Hermione discuss their secret plan which will "break about fifty school rules" while walking down a corridor crowded with students. The only reason they aren't overheard is that they are leaning closely toward each other. In the book, they talk about it in private.
- Juliana: When Cobra discovers Juliana's secret, he rushes to tell Gusano and Moni. He leans forward and just those two hear him despite all of the kids being in the same room. When the kid next to Moni asks what they are talking about, Moni does the same as Cobra, so nobody else would hear. It's eventually all unnecessary because Cobra gets fed up and yells it to everyone.
- Mary Poppins: Near the beginning of "Sister Suffragette", Mary bends to first Ellen and then Katie to tell them that while they love men, as a group they can be very dumb. She sings that line with a mischievous smile on her face.
- Monty Python and the Holy Grail: Played for Laughs. When the French knight is bawling over the castle wall to Arthur and his knights that they already have their own Holy Grail, then turns to the other knights with him on the wall and whispers behind his hand, "I told them we've already got one!" and they all cover their mouths and guffaw, clearly learning this for the first time.
- Not Another Teen Movie: The hero, Jake, admits to the bet of turning Janey into the prom queen, when Austin leans into Janey and whispers, "Jake is going to admit betting on you" into her ear.
Literature
- That Hideous Strength: Played for Laughs as it's the resident cloud-cuckoo-lander who does it to get food. He rambles to Mark in a mysterious tone to make him think he's talking in code.
- The Mediator: Adam adopts a confidential tone when he reveals to the secretary that his sister Suze is adopted.
- Star Wars Expanded Universe: A lampshade is hung on this when C-3PO leans over in an "overly conspiratorial" fashion in a novel.
- Temeraire: Subverted. Temeraire attempting to whisper conspiratorially and the narration noting that a twenty-ton dragon's whispers can still be heard by anyone remotely nearby is a Running Gag.
- Words of Radiance: Syl reveals the trickiness of doing magic—casters ought to be consistent lest they break their brains—while bending toward Kaladin as if it were a closely-guarded secret.
Live-Action TV
- 'Allo 'Allo!: It's a running gag how, upon donning a new Paper-Thin Disguise, Monsieur Roger LeClerc would approach one of his acquaintances and whisper his Character Catchphrase—"It is I, Le Clerc!"
- Animorphs: The heroes hold most of their meetings in a crowded arcade/restaurant, where anyone around them could be one of the bad guys. It's justified, in a sense, because such places have tons of background noise that make it difficult to eavesdrop, especially if the characters are cluttering close to each other. In the books, they logically meet in the privacy of a barn. They only meet in public spaces when the information is not sensitive.
- Community: Troy leans close to Abed to whisper something, while the rest of the study group is gathered around them. Annie subsequently prompts Abed to reveal what Troy said to him. Turns out, it was, "I know you hate when people do this in movies."
- Criminal Minds: In "Memoriam", Reid relives some pressure off Henry, whose mother is hung up on him attending Yale, by whispering to him that he (Reid) can get him (Henry) into Caltech with a call. Henry's mother JJ remains none the wiser.
- Frasier:
- 'The 2000th Show': In an effort to comfort Daphne, Martin admits having broken lots of Frasier's stuff after looking around the room and leaning toward her.
- "Kissing Cousin": Frasier and Martin take advantage of both Daphne and Niles who are helping them with their accumulated housework. As Niles tends to automatically do chores because his policy is to clean up messes as one goes, Martin stops a guilty Frasier from helping him because he knows Niles will end up making them dinner. He does so by getting closer to Frasier and whispering in his ear.
- Friends: The most blatant examples of this are from this series, where it would seem the characters are all deaf, and an invisible soundproof wall was found just behind all sofas. And even menus when the characters being discussed are sitting at the same table.
- Hannah Montana: Averted a couple of times, and even receiving a Lampshade Hanging or two.
- Married... with Children: This happens all the time, typically when the family is mocking Al in front of his back, so to speak. Given that it's Al being talked about, he might still be able to hear them. They just don't care.
- Seinfeld: Parodied in "Lip Reader" when George and Jerry go to great lengths to hide their mouths from a deaf lip-reader in order to talk about her when she is sitting at the same table... only to find out she was perfectly aware not only of what they were doing but what they were saying as well.
- Slings & Arrows: Cyril regales Frank with an anecdote about Geoffrey losing it during the gravedigger scene of Hamlet. He leans toward Cyril for added dramatic effect when he gets to the juicy details.
- The West Wing: Defied in "In This White House. On Ainsley's first day, she has to meet with two Jerkasses about a stupid thing they did and suggests that they go out into the hallway rather than discuss it in their open-plan office. Being new, she doesn't realize that the hallway will be as full of people walking and talking as any given room. She leans in and says, "Okay, we'll keep our voices down." One Jerkass leans in long enough to sarcastically say, "Okay," then straightens up and they both spend the rest of the scene in normal poses talking at normal volumes, while she continues to lean and whisper. No respect, no Pose of Silence.
Music
- Buttress: Subverted in "Brutus". The titular protagonist approaches Julius Caesar from behind and leans to his ear to whisper a rage-filled, envy-driven speech ("Or am I just wishing I could be like you? that the people would see me too as a poet and not just the muse"). However, judging by Caesar's nonreaction, it's clear that neither he nor the townspeople can actually hear her.
- Oliver!: In the outro of "The Arrangement", Oliver breaks into a whispered Irish brogue to assume the role of an impish vendor trying to make a deal with the listener for a sneezing remedy.
Radio & Podcasts
- Cabin Pressure: In an "Are You Pondering What I'm Pondering?" moment between Douglas and Martin, Arthur suddenly buts in and closes ranks to tell them that their secret idea might just work despite not knowing what's going on.
Video Games
- Command & Conquer: Red Alert: Some of the Soviet cutscenes have Stalin's advisor (played by Joseph D. Kucan) leaning in to whisper in his ear while everyone else ignores him. At the end, he's considerably more proactive, holding a gun to Stalin's head and revealing that no, he's not played by the guy who played Kane in Tiberian Dawn, he is Kane.
- Final Fantasy VII Remake: In the tenth chapter, Tifa assures Aerith that Cloud can carry all the stuff they buy on their shopping day once they exit the sewers. She bends toward Tifa so Cloud can't hear her what she's saying; presumably because he'd be opposed to the idea.
- Total War: Warhammer II: Skaven living in cities with low public order whisper conspiratorially to you that it's time to Eat the Rich.
