Trick Dialogue

A subversion of the most fundamental aspect of Dialogue: whether a character is talking to someone else or not.

Commonly, a character will appear to be making a brave confession, and then be revealed to have just been practicing before a mirror. Or, he will seem to be explaining his life to someone, and then be shown to be talking to a gravestone.

Alternatively, a character will clearly be talking to himself, but we find out that someone just happened to overhear. (Bonus points if it was the intended recipient of a difficult request.) This can follow on the first kind for a Double Subversion of dialogue.

Visual media typically use a Reveal Shot, often a Closeup On Head, to execute Trick Dialogue. Compare Fourth Wall Psych (where the character appears to be speaking to the audience but is actually talking to another person). See also Not So Dire.

Anime and Manga

 * Ryouga Hibiki does this all the time, pretending that various random objects are Akane in order to practise asking her out and/or confessing his love for her. He doesn't seem to mind (or notice) the way people stare.
 * Ranma himself also does this from time to time, often to indulge his ego as he imagines the other party's response. Invariably, Akane is always there to catch the tail-end of it, making him backpedal and either deny everything, or try (and fail, badly) to reuse the dialogue.
 * The Mahou Sensei Negima chapter where Nodoka confesses her feeling to Negi began with this. Close-up of Negi seemingly asking what she wants. Close-up of Nodoka requesting him to spend the free activity day together with her. Wide-area shot showing Nodoka practicing in front of a Negi bobble-head in her room.
 * In Naruto, when it appears as if what he's saying about his life just being a series of failures is an Inner Monologue, but we then see someone else respond revealing it was actually him talking to someone  in a flashback.

Comic Books

 * A rather memorable variant happened in one Usagi Yojimbo comic. In trying to get out of the rain, Usagi came across the swordswoman Inazuma telling her life's story to some of her friends. By the time she is finished, the rain has let up, so Inazuma bids them farewell and heads out. Usagi makes an aside about the story to one of the "friends"... only to discover that all four of them are dead -- bounty hunters who had been trying unsuccessfully to kill Inazuma.
 * Used elsewhere in Usagi Yojimbo when Usagi goes to return a small trinket to a fellow member of Lord Mifune's army.
 * A frequent source of comedy in Dork Tower. One story begins with Gilly and Matt preparing for a blind date. We then see them at a table talking, and seeing how they share lots of common interests and hobbies. The final panel shows that they are actually sitting at two different tables, each talking to someone else who think their hobbies are weird.
 * Inverted in another story, where Matt starts off talking to Ken about how Gilly is his ideal girl, while Walden is talking to a stranger about finding a Nice Guy for Gilly. After a page and a half, it's revealed that Matt and Walden were talking to each other, not realizing that they're both referring to the same Perky Goth (or how Matt would be perfect for her).
 * At the end of the Firefly comic Those Left Behind,
 * Bron does this in Scion when it looks like he's Breaking the Fourth Wall to make a soliloquy, but he's actually talking to.

Film

 * The movie Cool Runnings uses this; Junior appears to be talking to his dad about his career, but it turns out he's just practicing. On the dog. When his dad does turn up, he gets completely thrown.
 * In Batman (1989), Bruce Wayne mouths "I'm Batman. I'm Batman" with a view to confessing to Vicki Vale, and an almost Ironic Echo of his first line of the movie, spoken to menace a Gotham thug.
 * In Stardust, Tristan gets fired from his job and practices by telling the mirror, only for his father to come in when he was telling the mirror. His father didn't mind anyway.
 * Much of The Sixth Sense turns out to be the "character talks to someone and doesn't realize they can't hear him" variety of this.
 * Near the beginning of Shaun of the Dead, Shaun and Liz have a frank discussion about Shaun's unbearable roommate, who, as it turns out, is cheerfully standing within earshot. They go on to discuss Liz's friends, who are then revealed to be sitting right next to them. ("No offense!").
 * Done in reverse at the end of Hot Fuzz:
 * In Reservation Road Dwight appears to be telling someone what he had done, but then the camera pans to show that he's recording a message for his son on a video camera.
 * After his wife's kidnapping, (which he arranged himself), Jerry Lundegaard in Fargo sounds like he's desperately trying to explain to his father-in-law that his wife has been kidnapped, but stumbling over his words. It turns out he was just trying to find the right way to sound worried before he actually picked up the phone.
 * In The Princess and The Frog
 * The Disney movie Oliver and Company features a scene in which Fagin is confidently describing his ransom plot... to Dodger. When he actually goes to Sikes' office, he barely manages to stammer it out.

Literature

 * Yes, literature. In the very first Aubrey-Maturin book, Aubrey tells all his troubles to his particular friend... who hasn't returned to the ship yet.

Live Action TV
"Giles: W-w-w-what I'm proposing is, um... and I-I don't mean to appear indecorous, is, is, um, a, a-a-a social engagement, um, a, a, a, a-a date, if you're amenable. (to himself) You idiot!
 * Carter's rant about reproductive organs in the Stargate SG 1 episode "Moebius, Part I". This was used partly to differentiate this version of Samantha Carter with the previous one, who had no problem uttering the same line during a briefing in the series' first episode, and partly as an in-joke.
 * Another episode had an interesting twist. Daniel, who is out of phase (read: invisible), is talking to his grandfather, Nick. Nick starts talking back, thinking that Daniel is a hallucination. Daniel continues replying, thinking that his grandpa is just thinking out loud. Eventually, it turns out that Nick can see Daniel. Yes, they managed to have a conversation without realizing it.
 * An episode of House featured Allison Cameron making a Freudian slip-up in front of a documentary crew by saying "I love House!" When next we see her, she's frantically trying to find some way of qualifying that statement without making matters worse and failing. On first reveal she is talking to a mirror; on second reveal, her current boyfriend is on the bench behind her looking put-upon for being forced to listen to this.
 * This happens to Giles in 'Series/'Buffy the Vampire Slayer'':

Buffy: Boy, I guess we never realized how much you liked that chair."


 * Done again a few seasons later when a certain character we know and kind of love practices confessing his love to Buffy by talking to a mannequin wearing one of her sweaters and a blonde wig. He makes it about four sentences into the imagined conversation before it degenerates into mutual (half-imagined) verbal abuse, and he winds up beating it over the head with a box of chocolates.
 * Also done with Xander in the opening of the first season episode, Prophecy Girl. Xander apparently asking Buffy out for a date is actually him talking to Willow, who is then revealed to be acting as a stand-in so Xander can rehearse his proposal to Buffy.
 * An entire episode of Angel has Lorne telling the story of the episode to a theatre - that, at the end, is revealed to be empty.
 * In season 2 of Battlestar Galactica Reimagined, politician-slash-beloved-terrorist Zarek talks in front of a mirror about the upcoming election in typical public speaking style. Then he turns, elaborating that he wants to run against the incumbent on a ticket with... current Vice-President Gaius Baltar.
 * Sara Sidle of CSI has done this at least twice.
 * The start of Spaced begins with Tim and Daisy apparently splitting up with each other. However, at the end of the scene, we see that they are in different locations, having completely different conversations. Tim is getting dumped by his girlfriend and Daisy is talking to a homeless man.
 * In the third season of Lost, Hurley gives a speech about how hard things have been on the island, and how sad everyone is. As we watch, the camera pans to reveal that he's talking to a grave marker.
 * Wolf from The Tenth Kingdom appears to be confessing his love in a very heart-felt mannor, unusual for him. We soon learn that he was reciting a speech from a book, trying to memorize it.
 * One episode of Scrubs was told largely by Dr Cox in flashback, against a neutral background, with the topic being his poor anger-management in dealing with the interns. From context, the obvioius conclusion was that he was talking to his shrink. But at the end he says "Well, unfortunately the only way I know how to teach is through fear. And I tell you this because I know that this particular shortcoming will invariably affect your life" and the Reveal Shot shows that he's been talking to his pre-verbal son.
 * Dr Kovac on ER spent the entirety of one episode narrating his feelings as if he were talking with a psychiatrist, only to be revealed as talking to a prostitute at the end.
 * In one episode of Babylon 5, after a Centauri warship attacked the station and was destroyed, Sheridan is shown giving a speech that starts out as an apology before veering into a rant about how he's glad he blew the ship to hell because they were firing on civilians, including their own people. The reveal, of course, shows that he's only practicing - whether he actually gave that "apology" or not is never shown.
 * Word of God says he didn't, but he would have. Later events of the episode rendered it unnecessary.
 * In one episode of Frasier, Frasier begins talking to someone about his feelings about Niles and Marris's divorce. As he's talking, that person walks away, so Frasier ends up talking to himself. By the end of his now monologue, he asks if the other person understands. That person has only that instant come back and gives an offhand 'Yeah' not having heard a word of Frasier's anguished speech. It happens once with his father in their apartment. He comes back after having gone to get a paper. It happens a second time in the coffee shop where Ros leaves him to talk to some friends, then comes back to his table.
 * Lois on Malcolm in The Middle appears to be giving her boys a heartfelt speech about how she just wants to know who set the dress on fire, sounding as desperate and kind as she can. The camera cuts back to show her talking to a mirror and then saying, "Nah, they'll never buy it."
 * An episode of Due South had Fraser and Ray get into an argument early one. Later, we see them both talking about their feelings, about how they manage to just frustrate each other, and it gradually becomes clear that they're both talking to themselves, in their own apartments.

Music
"Hitting every pocket on my shirt, pants and overcoat
 * They Might Be Giants uses this in their song "Till My Head Falls Off":

And I'm hitting them again but I don't know where I put my notes

Clearing my throat, and gripping the lectern I smile and face my audience

Clearing his throat and smiling with his hands on the bathroom sink."

Video Games

 * Apollo Justice : Ace Attorney has a very odd example of this, where two characters are shown facing each other and dialogue shows up in the text box. Because of what has gone on earlier in the game, it seems as though the speaker is one person, when it's actually the other. Although if you think about it, the facts don't quite match up, so it's possible to guess the identity of the real speaker.
 * In the same game, briefly, and the appropriate sprite appears for a moment.
 * The Meet the Soldier video for Team Fortress 2 has the eponymous soldier lecturing a platoon on his hilariously inept understanding of military history ("'If fighting is sure to result in victory, then you must fight!' Sun Tzu said that, and I'd say he knows a little more about fighting than you do, pal, because he invented it!"). The camera switches views at the end, revealing the "soldiers" to be a row of severed heads on a fence.

Theater

 * Subvertion: Argentinian Comedic Group Les Luthiers has a whole sketch about a guy who declares to his love, talking to a empty chair. Since is theater, and the whole group is male, no one is surprised about this fact and the espectators asume is in fact the real thing.

Webcomics

 * Dominic Deegan used both kinds in one strip. Dominic's defensive justifications for his actions are revealed to have been aimed at his cat Spark instead of his girlfriend Luna. (Actually, the cat understood, but he just didn't care.) Also, Nimmel's Rousing Speech to himself in a mirror is revealed to have been overheard by Luna.
 * Both kinds were also used earlier, when Szark Sturtz poured his heart out to what was revealed to be a Dominic doll -- and then Jayden revealed that she'd been standing nearby and heard the whole thing.
 * Used in Sabrina Online when Zig-Zag appears to be telling Sabrina how she really feels... only to finish with, "I also wonder how hard it would be to tell you this while you're awake."
 * A confession of love somewhere in Narbonic.
 * This strip of Order of the Stick. Used again, more recently, and rather heartbreakingly.
 * This strip is a bit of a subversion since Roy is actually talking to the person he means to address, but it still fits since Also the first major Tear Jerker in the series. Hoo-boy.
 * One of the last comics of Queen of Wands combined this with Not So Dire (and instead of the Closeup On Head Shot, used shadows) to give Aeire's readers' chains just one more little yank.
 * In Sluggy Freelance, Bun-bun is once shown lying on a couch talking about his thoughts and problems as if to a therapist, even though he's the last person you'd ever expect to do that. It's then revealed that he was talking to someone, because he needed someone to talk to to clear his thoughts - but that someone is Kiki, who immediately forgets everything he said when he shows her some shiny new car keys to play with. Bun-bun has also had his ears plucked to block out Kiki's incessant hyperactive chatter in response to what he's been saying.
 * This strip of Adventurers. Khrima is just practicing his Evil Gloating.

Web Original

 * Red vs. Blue: Recreation pulls this with Caboose and Donut. Donut stands behind Caboose while the latter seems to ask an A.I. unit if it "ever feels like you're being watched by someone." As the episode fades out, he adds "Donut, I'm asking you a question."

Western Animation

 * Parodied in Family Guy: Peter asks his boss to come to dinner at his house and he's clearly practicing in a mirror. The Reveal shows that he's practicing in a mirror in his boss's office. His boss accepts.
 * Avatar: The Last Airbender: Zuko does this in "The Western Air Temple", practicing his "Hi, I've made a Heel Face Turn" speech in front of a frog.
 * And then subverted for laughs when he walks up to Aang and company and gives the first bit of the same speech, intonation and all.
 * The first episode of Clerks: The Animated Series used this type of gag; A manhole cover is lifted partially open from the inside, and we hear Dante and Randall speak to one another while two sets of eyes are shown peeking out. Cue Dante and Randall walking past from offscreen.
 * In the Rocko's Modern Life episode "A Sucker for the Suck-O-Matic", Rocko appears to be getting fed up with his slacker friend Heffer ("You're useless, and pathetic! Like... a useless and pathetic thing!") and is preparing to beat him to death, but he's really just frustrated that his old vacuum cleaner has broken down again.
 * In the Kim Possible episode "Emotion Sickness", a montage of Ron expressing his thoughts and concerns about Kim's sudden (Moodulator-induced) romantic interest in him ends in the reveal that he's talking to Mr. Barkin, who demands to know, "Stoppable, how did you get in my house?"
 * In the episode Candace Disconnected on Phineas and Ferb, Candace appares to be talking to her best friend Stacy on the phone (complete with mentioning her name and having an actual conversation), only for her head to turn and reveal to the audience that... she was talking into her own hand all along.
 * Also in the Lemonade Stand, she sees a girl waving to her, calling her best friend, even though she doesn't know her, she accepts... only to find out she was talking to someone behind Candace.