My God, You Are Serious

"Leela: Doesn't it bother you even a little to be taking advantage of your girlfriend's trust? Bender: Ha ha ha! Oh wait, you were serious... Let me laugh even harder. HAHAHAHAHAHAHAHAHA!!"

- Futurama

The inversion of I Was Just Joking. A character says something that sounds insane or absurd. Another character either laughs or snarks You Have Got to Be Kidding Me! - then realizes with alarm that the other character wasn't joking.

Expect to hear this phrase every time a Deadpan Snarker is confronted with the Zany Scheme of the week. Badasses who say things like "I'll just have to bust in and take them all out, then!" can usually expect this reaction, too.

Contrast Ha Ha Only Serious.

Anime and Manga

 * Kyon's reaction to Nagato's big revelation in Suzumiya Haruhi.
 * The very existence of Powerpuff Girls Z was thought to be a joke, as a preview was first seen on April 1st.

Comic Books

 * In Destination Moon, when Calculus says he's finishing plans for a rocket that will land on the moon, Captain Haddock has a big hearty laugh about it, and facetiously suggests, "You are taking passengers, I hope?" Calculus replies, "Why else do you think I asked you to join me?", utterly stunning Tintin and the Captain.

Film
"James Bond: Ejector seat? You're joking! Q: I never joke about my work, 007."
 * Goldfinger provides this variation:

"Angel Eyes: (to Baker) Oh, I almost forgot - he paid me a thousand. I think his idea was that I kill you. (both laugh) Angel Eyes: ...But you know, the pity is when I'm paid, I always follow my job through. You know that. Baker: No! Angel Eyes!"
 * From The Good, the Bad and the Ugly:

"Spock: It would be impossible to discuss the subject without a common frame of reference. McCoy: You're joking! Spock: A joke... is a story with a humorous climax. McCoy: You mean I have to die to discuss your insights on death?"
 * Strangers on a Train starts with this. Bruno suggests that he and Guy trade murders, but Guy doesn't realize Bruno was serious until after his wife shows up dead.
 * This same scenario is played with in Throw Momma from the Train by characters who've seen the above movie.
 * In National Treasure: Book of Secrets, Benjamin Franklin Gates announces his intention to kidnap the President of the United States, since the President has access to the titular book. As in many examples of this trope, his friends think he's joking at first, and then try to talk him out of it when they realize he's serious.
 * Star Trek IV: The Voyage Home has the following, after McCoy asks Spock to tell him about the afterlife:

"Ted Striker: Surely, you can't be serious. Dr. Rumack: I am serious. And don't call me "Shirley"."
 * Tremors 2: Aftershocks: Kate's reaction to the ridiculously huge amount of weapons and explosives Burt Gummer has brought in to fight the creatures is laughter... until she notices how everyone else remain deadly serious and realizes her mistake.
 * A classic subversion in Airplane!:

"Tevye: Thank you, your honor. You are a good man. If I may say so, it's too bad you're not a Jew. Constable: [laughs] That's what I like about you, Tevye. You're always joking."
 * In Fiddler on the Roof:

"Po: And here I am saying you got no sense of humor... What, you're serious?!"
 * Awkward silence ensues as the Constable realizes Tevye was not joking.
 * In Kung Fu Panda, after Shifu tells everyone that Po is the only one who can stop the now-escaped Tai Lung.

"Janine: Hello, Ghostbusters. Yes, of course they're serious!...You do? You have?...No kidding?"
 * A variant occurs in Ghostbusters.

Literature
"'And finally, I must tell you that this year, the third-floor corridor on the right hand side is out of bounds to anyone who does not wish to die a very painful death.' Harry laughed, but he was one of the few who did. 'He's not serious?' he muttered to Percy. 'Must be,' said Percy, frowning at Dumbledore."
 * Harry Potter and the Philosopher's Stone:

""But you've left out one of the chief characters: Samwise the stouthearted. 'I want to hear more about Sam, dad. Why didn't they put in more of his talk, dad? That's what I like, it makes me laugh. And Frodo wouldn't have got far without Sam, would he, dad?'" "Now, Mr. Frodo," said Sam, "you shouldn't make fun. I was serious." "So was I.""
 * In Wizard and Glass, a young Roland gets sent off to the supposedly safe backwater area of Mejis. Before he goes his father tells him to keep an eye out for one of the 13 balls of Maerlyn's Rainbow, powerful magic tools, because the leader of the evil rebellion is suspected to have one. Even Roland, who is famous for not having a sense of humor, laughs at the possibility of happening to run into one and assumes his father was joking, but good old dad just stares him down and says something along the lines of "Roland, do you really think I'd send you off with a joke like that?"
 * "For love of God, Montressor."
 * Choose Your Own Adventure book Journey to the Year 3000 starts like this.
 * Used lightly in The Lord of the Rings:


 * Mansfield Park: Fanny can't believe that Henry Crawford's marriage proposal is not a horribly distressing joke but a twice-as-horribly distressing sincere proposal until the next day. Cue the Marry for Love rebelliousness in typical Jane Austen tradition.
 * Inverted in Ciaphas Cain: in a Mechanicus dam/shrine protecting an extremely powerful artifact in danger of being stolen by Chaos, one of the commanders suggests blowing up the dam if worst comes to worst. The head magos, understandably upset, asks if maybe an orbital strike wouldn't be better (without sounding sarcastic). The commander replies that none of the ships could get into position for long enough.

Live Action TV
"Lorelai: "Café au lait"? Is that's how it's spelled? Hmm, I always thought it was ¡Caffee olé! You know, like, "Coffee, alright!" Christoper: (incredulous) You're kidding! [beat] You're not kidding. [beat] You are kidding. [beat] (unnerved) I can't tell if you're kidding! Lorelai: I'm a woman of mystery."
 * Dr. Cox says this fairly often on Scrubs
 * On Friends Ross has been spending the entire episode asking people if they want to watch a Ukrainian film with him, only to be laughed at. At the end he bumps into Mona, and he invites her to the movie. Mona laughs for a bit, then says "Oh, you're serious. Sure!"
 * In the series Necessary Roughness when the psychiatrists suggests hypnotism, the football player has this moment.
 * Characteristic moment on Gilmore Girls between Lorelai and her not-quite-soulmate Christopher:

"Britta: Shirley, if that really is your excuse, I'll plan your wedding for you! Shirley: (Manic laughter) Title Card: Literally two full minutes later... Shirley: (Catches her breath and hands a water bottle back to a concerned passerby, still laughing) (to passerby) Ooh-hoo! Thank you. (to Britta) Oh my good God... Thank you for that... Britta: (deeply offended) I was serious! Shirley: (stares incredulously) Title Card: One minute later... Shirley: (deadly serious) Britta, you're not planning my wedding."
 * Community takes this Up to Eleven in the episode "Urban Matrimony and the Sandwich Arts":


 * In one episode of Kaamelott, the notoriously stupid, lazy and cowardly Perceval and Karadoc realise that they haven't done anything useful for a while and volunteer to be part of a highly dangerous mission. All the other knights burst out laughing, and are rendered speechless when they realise they were serious.
 * Done in a very, very serious way in an episode of The X-Files. An alien assassin was sent to earth to kill a rogue alien who chose to stay on earth as a baseball player. An officer asked where the assassin came from, and laughed at his reply of 'Mars'. Cue the officer's Oh Crap when the assassin's face remained deadpan, implying he is not joking.
 * In an episode of Malcolm in the Middle, Malcolm's teacher tells Lois that she thinks Malcolm doesn't want to participate in folk dancing because he's self-conscious about his body. Lois' reaction is to laugh before lapsing into complete serious mode when she says, "Oh, you're serious." When the teacher says that she is, Lois continues chuckling to herself.

Newspaper Comics

 * In a Dilbert strip, Asok laughs at his boss's complaint that 40% of sick days are taken on Mondays and Fridays before realizing his boss is actually that stupid.

Video Games

 * Alistair can have one of these moments when you tell him.
 * In Alpha Protocol, you find out early on that there are plans in place to dismantle it if something goes horribly wrong. If you ask what happens to the people, you get one word: "Expendable." You respond with this trope.
 * In Deus Ex Human Revolution, Adam Jensen responds with this trope when

Webcomics
""Lena, go make me a Closed sign while I reinforce the shutters so they don't go all Night of the Living Dead on us." "Is that all necessary? Won't they see the closed shutters and sign and figure out we're not open for business?" "Hahaha ... Oh, wait. You were being sincere. Allow me to redirect my mocking laughter to you. You fool.""
 * Suicide for Hire: The snack stand Arcturus is temporarily working in is closed:

"Watto: What are you offering for that information? Annie: To not laser sword your leg off. Watto: You wouldn't. Annie: * Death Glare* Watto: You would!"
 * Annie and Watto have an exchange in Darths and Droids:


 * In Penny Arcade, a little commentary about the Universal Media Disk.
 * Done to agonizingly awkward effect on Questionable Content.
 * Done in Sequential Art when Hilary realizes the extent of Pip's lack of fashion sense, here.

Web Original
"Spencer (pulling on black ski mask): If Jonas doesn't succeed, I'm going in. (Taylor laughs, then stops quickly) Taylor: Oh my God, you're serious!"
 * In the Lonelygirl15 episode "Mission Possible":

"Paradox: What destroyed the world was...card games. Yusei: What? Paradox: That is right, card games. Yusei: You're serious? Paradox: Yes, very."
 * Taylor's reaction is understandable, since Spencer isn't a badass - he's a Nerd who can't even exercise.
 * From the Bonds Beyond Time Abridged comes this gem between Paradox and Yusei.

Western Animation
"Pleakley: Who is going to control [Dr. Jumba]? Councilwoman: You are. (Walks away) Pleakley: (laughs) Very funny. (Sees that she's gone) Oh, you're not joking!"
 * If memory serves correctly, Lilo and Stitch had an exchange in the beginning between the Councilwoman and Pleakley.

"Jasmine: Well, I know plenty about the real world, don't I, Genie? Genie: (puts on a trenchcoat, hat, and gangster accent) Sure, you know all about the dark, dank underbelly of this sleazy city of sin! (returns to normal, laughs) Jasmine: (Death Glare) Genie: Oh ... you're serious."
 * In the Aladdin Animated Series, Jasmine and Aladdin get into an argument about how her privileged upbringing has left gaps in her education concerning how most people live their lives, and Jasmine turns to the Genie to back her up.

"Guan: This is the home of the famous Chase Young. Dojo: HAHAHAHAHAHA!!! I thought you said "Chase Young"! Guan: I did."
 * The Wasp does this in Avengers Earths Mightiest Heroes, when SHIELD asks the team to go into a Gamma radiation-infested prison full of escaped supervillains.
 * She does this again in a later episode, after Iron Man says Nick Fury suspects one of the Avengers of being a Skrull in disguise.
 * In the My Little Pony Friendship Is Magic episode "Secret of My Excess", Applejack initially laughs at Twilight Sparkle's claim that Spike is running rampant, until she sees it for herself.
 * Xiaolin Showdown: When Dojo asks Master Monk Guan why he was brought to a hidden fortress.


 * Cue Oh Crap from Dojo.