->'''Homer:''' All right, Marge, I'll tell you, but first you have to promise you will not get mad.
->'''Marge:''' I promise I ''will'' get mad, because I always do when you make me promise I won't.
-->--''TheSimpsons'', "Lisa The Greek"

Two characters have a conversation like this:

-->'''Character A:''' I need some advice from you.
-->'''Character B:''' Shoot.
-->'''Character A:''' Promise me you won't laugh, okay?
-->'''Character B:''' Okay then.
-->'''Character A:''' How do I get rid of this rash in the shape of lovehearts on my left buttock?
-->'''Character B:''' Bwahahahaaha!
-->'''Character A:''' You promised you wouldn't laugh!
-->'''Character B:''' Sorry dude, I didn't mean to.

Sometimes Character B is Character A's friend; they may try to unsuccessfully stifle the laugh. If they're TheRival (or The {{Jerkass}}) then they'll probably just be in peals of laughter. "Promise me you won't laugh" isn't the only scenario, though; sometimes it's substituted with "you won't scream", "you won't panic", "you won't get mad" or something similar. Almost every time the person goes back on the promise. Beginning to be subverted more and more often in the style of ''TheSimpsons'' quote at the top of the page, or by someone saying "I'm not promising anything till I hear what you say."

Another variation on the trope is a conversation that goes something like this:

-->'''Character A:''' What happened?
-->'''Character B:''' Trust me, [[YouDoNOTWantToKnow you don't want to know.]]
-->'''Character A:''' No really, tell me.
-->'''Character B:''' *insert gross/inappropriate/silly/ridiculous story here*
-->'''Character A:''' ... you were right. I didn't want to know.

See also PreemptiveApology, EmptyPromise.
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!!Examples:

[[foldercontrol]]

[[folder: Anime ]]

* ''{{Kanon}}'', [[spoiler:That's one way to reunite with your NotQuiteDead girlfriend...]]
* ''Lightnovel/FullMetalPanic'', Sousuke have forgot to bring Chidori's notebook, and he promised her that she must not panic no matter how bad the situation is. Instead, she went into UnstoppableRage

[[/folder]]

[[folder: Film ]]

* ''Film/{{Casper}}'', (1995 movie) has Casper muffle Kat and explain his position as a friendly ghost, and offered to un-muffle her if she promised not scream. Of course as soon as she could speak again, she screamed.
** Averted the second time he does it.
* ''Film/TheSixthSense'': Cole and his mother are having a conversation about a pendant of her mother's. Cole's mother is sure Cole's taking the pendant. She tells him, "I promise I won't get mad," and she asks him if he took the pendant. He tells her no -- as he tells her every time. And naturally, she gets angry with him.
* Subverted in ''Film/WakingNedDevine'': Finn asks Maggie to read some of her poetry (actually, greeting card texts) to him. She makes him promise not to laugh... and then breaks into laughter after her own first word.
* ''Film/RobinHoodMenInTights'': Maid Marian pleads with Robin not to enter the archery contest that she knows is a trap. Of course, the promise of facing an undefeated archer is too tempting for Robin Hood.
--> '''Maid Marian:''' Robin, promise you won't go.
--> '''Robin Hood:''' All right, I promise you won't go.
--> '''Maid Marian:''' Thank you.
--> '''Ahchoo:''' But wait a minute, Robin, didn't you just...
--> '''Robin Hood:''' Cool it...
--> '''Ahchoo:''' Chilled.
* Near the climax of M. Night Shyamalan's ''Film/TheVillage'', right before Edward Walker shows his daughter Ivy [[spoiler: the monster costumes they keep in the shed]]: "Do your very best not to scream."
* In ''Film/PulpFiction'', Mia Wallace calls Vincent out on asking her not to be offended by a question, saying that if she promises not to be offended and then ''is'' offended, he'll have forced her to break a promise.
* In ''Film/YoungFrankenstein'', the doctor asks his assistant Igor (pronounced eye-gor) to tell him whose brain they put in the monster. After the doctor promises not to get angry (even emphasizing the "not") Igor tells him it was "Abby somebody. Abby Normal I think". The doctor then attempts to strangle him.

[[/folder]]

[[folder: Literature ]]

* In the Literature/{{Discworld}} book ''Discworld/GoingPostal'', Moist von Lipwig reveals his BoxedCrook backstory to Adora Belle Dearheart, including the fact that he was the crook whose forgeries got her fired from her previous job at a bank. He first makes Adora promise not to make any sudden movements, because "I think that in a few seconds you'll try to kill me." Played with in that Adora ''does'' hold to this promise, with some reluctance.

[[/folder]]

[[folder: Live Action Television ]]

* Subverted in ''Series/TheITCrowd''. After a masseur kissed Roy on the arse, he was about to tell Moss but first made him promise not to laugh. Afterwards, Moss is disgusted that Roy would think he'd find it funny.
* ''Series/{{Angel}}'' played this trope adorably in "Waiting in the Wings". A self-conscious Gunn makes Fred promise not to laugh at him in his tux. She promises, then immediately bursts out laughing because he's "just so pretty." This foreshadows their hook up later in the episode.

[[/folder]]

[[folder: Radio ]]

* ''TheGoonShow'': In the episode "Shangri-La Again", Major Bloodnok is supposed to have obtained an aeroplane to fly the Embassy staff to safety:
-->'''Bloodnok:''' The plane...the plane. Ooo! Ooo heavens!
-->'''Seagoon:''' What's up?
-->'''Bloodnok:''' Look - if I tell, promise you won't blow up?
-->'''Seagoon:''' I promise.
-->'''Bloodnok:''' I forgot to order it.
-->'''GRAMS:''' Explosion.
-->'''Bloodnok:''' You promised!

[[/folder]]

[[folder: Theatre ]]

* ''Film/{{Big}} The Musical'' has an extended sequence in the song "This Isn't Me" where Josh, suddenly an adult, asks his mom not to turn around yet, and not to scream when she does. She instead asks why she would scream, and of course does just that when she sees him.

[[/folder]]

[[folder: Video Games ]]

* ''FireEmblem'' has a support conversation between Eliwood and Hector, where Hector's thinking of a dream he had and Eliwood asks him to share it. His response before doing so: "Laugh and I'll kill you."

[[/folder]]

[[folder: Western Animation ]]

* ''{{Braceface}}'', "Leap of Faith" (last episode), "promise me you won't panic" (or "freak out", or something similar) when Alden tells Brock he's fallen back in love with Sharon.
* ''TheSimpsons'', "Lisa The Greek", subverted (see quote).
** In one of the original Tracy Ulman shorts, Bart gets all of his hair cut off at the barbers. He comes home wearing a bag on his head, and makes the family promise not to laugh when he takes it off. Natually, they guffaw hysterically when he does.
* ''TransformersAnimated'', Return of the Headmaster:
-->'''Sentinel:''' I need you to come to my position. And promise me one thing - that you won't laugh!
-->'''Optimus:''' [sees Sentinel - as a head, victim of the Headmaster, and burst into hysterical laughter]
-->'''Sentinel:''' You promised you wouldn't laugh!
* In ''WesternAnimation/SharkTale'', Lenny makes Oscar promise not to laugh before telling him how he's different from other sharks. He's a vegetarian. While Oscar does snort for a split second, he takes a deep breath and more or less manages to keep his promise.

[[/folder]]

[[folder: Web Comics ]]

* ''Webcomic/TheAdventuresOfDrMcNinja'' combines it with ImplausibleDeniability [[http://drmcninja.com/page.php?pageNum=47&issue=15]].
-->'''Dr. [=McNinja=]:''' You can '''talk?'''
-->'''Motorcycle:''' Promise you won't be upset?
-->'''Dr. [=McNinja=]:''' Yes.
-->'''Motorcycle:''' Yes.
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