Arthur: Right, but it's not your idea, because you know I gave it to you.
This is about a phenomenon of your very thought process: telling someone not to think about something will inevitably and involuntarily lead to them thinking about it. Telling yourself not to think about something may be even more futile, as by thinking about not thinking about it, you are thinking about it.
The suggestion that you should not be thinking about something is, in itself, sufficient to induce thinking about that thing. No other provocation is required—you don't have to be surrounded by elephants for the old schtick to work.
For instances when people can't stop thinking about some aspect of a person because it is so very noticeable, even if they don't want to mention it due to politeness, see Ignore the Disability. When thinking about a particular action makes it more difficult than performing the action unthinkingly, you are faced with the Centipede's Dilemma. Telling someone not to do something in hopes that they will decide to go and do it is plain ol' Reverse Psychology, or one of its Sub Tropes.
This phenomenon is actually a direct result of how the human brain is wired. Neurons that are used to interpret words like "elephant" have synaptic connections to the neurons used to picture and think about the concepts those words represent; if they weren't, verbal language itself probably couldn't function. Basically, the brain cannot visualize the lack of something without thinking of that "something" first. See Language Equals Thought.
In terms of real-life Reverse Psychology, those with weak impulse control who are told "do not do the thing" get hung up on "the thing" they are told not to do; as a result, they can't stop thinking about "the thing", and thus are more likely to do it, even if consciously trying to avoid it.
Thus, a good way around this problem is to, instead of discouraging someone from thinking of X, encourage them to think of Y instead.
- This idea is incorporated into the powers of Pakunoda of the Phantom Troupe in Hunter × Hunter. Her ability as a Living Lie Detector works by asking a person questions while she is physically touching them, allowing her to read their memories as they answer. Even if you know full well going in that the question she's going to ask is one you don't want to answer, you won't be able to help thinking of the answer as soon as she asks the question, giving her what she wants regardless of whether you're honest or not.
- In the card game Girl Genius: The Works, the action on the Phil Foglio card is "Do not think about a monkey."
- Buck Godot: Zap Gun for Hire has one at the end of a story where the Prime Mover tells a reporter that if she even thinks about the events that just happened (which would reignite the war they just barely prevented), her head will explode. She nervously jokes that he can't be serious; he suggests a lobotomy.
- The DCU: At the climax of the Emperor Joker storyline, Superman mentions this when he finally has his "Eureka!" Moment and realizes the "rule" that lets him defeat The Joker: Joker has his own "white elephant" — Batman, without whom he can't even define his own existence. Which means that even if he has godlike powers, Batman's really the one in charge and Joker's nothing more than an annoyance.
Superman: White elephants... the joke — "Don't think of white elephants...?" And it's all you can think of. White elephants.
Joker: How many times do I have to tell you people, that's not a joke! It's a short-term mnemonic cognition gag! Philistines, everywhere I go!
- In the storyline Ends of the Earth, this is how Spidey takes control of Sandman's form. As he explains "This I don't mind telling you. In fact, you knowing only helps. You just got pink hippo-ed, Sandy. We're transmitting images across your brainwaves, putting pictures in your head. Try not thinking about 'em!"
- In Ultimate Spider-Man, Jean Grey congratulates Peter Parker on being the first man she's met in months who didn't visualize her naked. We then get a page and a half of Peter making increasingly awkward faces while Jean looks more and more disgusted and angry. You'd think a telepath would have a better understanding of how people's minds work.
- Calvin and Hobbes: One strip shows Hobbes warning Calvin about a bee on his back and advising him to stand still and try not to imagine that it could quite possibly crawl into his pants. Naturally, the last panel shows Calvin leaping into the air with a yell of pain.
Hobbes: He imagined it.
- In one The Far Side strip, a man visiting a hospital patient in a plaster cast says, "You're not itching anywhere are you? Because you can't scratch you know. Don't even think about itching, it'll drive you nuts."
- In a Garfield strip, when Jon and Garfield are at Irma's diner:
Irma: Here's your egg, hon. Whatever you do, try not to think about where it came from.
Jon: Have an egg, Garfield.
Garfield: Too late. I already thought about it.
- In the Red Dwarf Smegazine strip "Living Memory", the crew comes across a machine that turns memories into reality. Lister decides to use it to recreate Kochanski. As he's doing this, Holly tells to "try not to think about any six-eyed, carnivorous, raging swamp beasts and everything'll be all right." Naturally, Lister thinks about this instead and conjures up said creature.
- In The Beginning of Reality, Harry and Draco are under mental attack by an unknown entity and Harry tries to transport them to a safe, non-embarrassing dream location. They end up witnessing his kiss with Cho.
Draco pursed his lips. Apparently when Harry was thinking "nothing embarrassing", he must have accidentally taken them to when he was kissing some girl. Draco would need to tell him that purposely "not thinking" about something immediately brought it to the forefront of your mind. It was like telling yourself not to think about big pink elephants. Obviously big pink elephants would show up in your head.
Harry: You cannot un-know something.
Rose: You can with magic.
Harry: Magic aside.
Rose: You mean like when you tell me not to think of pink fluffy bunnies and that's all I can think about.
- In Foobar137's "Don't Think of a Purple Elephant", Ferb invokes the trope in an attempt to make a Relationship Upgrade happen at a specific time. By betting Phineas that he will not kiss Isabella before that specific time, he renders Phineas incapable of thinking of anything else until he kisses Isabella just after the time expires, winning a much larger bet for Ferb.
- Harry Potter: Frost Fire:
Amelia: It's alright. Just a word of advice. Don't stare at the goblins.
Danielle: Great. Now I'm gonna stare. Do you understand how Pavlov works?
Susan: What's Pavlov?
Danielle: I'll demonstrate it with a game. Don't think about cats.
Susan: Easy! Wait, dang.
- If Wishes Were Ponies:
And no one knew where the twins were. Or what they were doing. It made Harry a bit nervous when he thought about that, so he tried not to think about it. It was a lot like trying not to think about an elephant.
- In The Last Son, one of the Martian Manhunter's favorite ways to telepathically extract information from someone is to simply get right in their face and tell them not to think about what he wants to know.
- Searching for the Power:
Harry: After you order your thoughts it will be harder for a Legilimens to access your memories without first figuring out how you organized them. He will still be able to get at the thoughts you haven't sorted yet though. And you know how the strangest thoughts can pop into your head without you meaning to think about them. Like if I said "Don't think of an elephant." What was the first thing that popped into your head?
- In Time Left Today, Harry tells Snape not to think of pink elephants and then pretends to read his mind.
Harry: You're thinking of — pink elephants.
Snape: My, my. Astonishing. A natural Legilimens.
- Unspeakably Recruited:
Harry: Well, first off, if you're going to keep top secret files in locked filing cabinets at the ministry, then you need to put up magical wards. Also I can read minds so stop thinking about your wife. Isn't it funny how I can make you think of your wife by mentioning her? Now for real lets sit down. My girl is starving and if we let Neville have a third Scotch he won't be much help during the conversation.
- In Encanto, Pepa's mood affects the weather. On her wedding day, her brother made an unfortunate comment:
Bruno says "It looks like rain"
In doing so, he floods my brain
Married in a hurricane!
- In episode 2 of Don Hertzfeldt's World of Tomorrow, after peeping on a memory inherited from one of her past lives, Emily-6 warns Emily-Prime not to think of a baby dinosaur later. Sure enough, when the two Emilys end up in Emily's "logic center", Emily-6 warns her younger self not to think of anything random and illogical, and Emily-Prime immediately thinks of a baby dinosaur.
- The Chronicles of Narnia: In the 2010 version of The Voyage of the Dawn Treader, Lord Rhoop escapes from the Dark Island, where the worst things you can imagine come true. When he boards the ship, he tries to warn them, but in doing so essentially says "Whatever you do, don't think about your greatest fear!"
- Used at the climax of Gamer. Castle triggers the systems keeping Kable under his control, but Kable is still able to talk... so he tells Castle, "Think of me stabbing you." Castle does so unconsciously, and Kable proceeds to knife him.
- Ghostbusters: The gang is on the roof facing off with Gozer, she tells them to choose her form, Venkman figures it out and tells the rest of the group to keep their minds a blank. Stantz meanwhile tries to think about the most harmless thing he can imagine: the Stay Puft Marshmallow Man, a snack mascot. Gozer promptly takes on that as her form and starts rampaging through New York City.
- In The Good Witch's Garden, a little girl is cured of nightmares by being told that she must not, under any circumstances, dream about bunnies. Three guesses what she dreams about, and the first two don't count.
- In The Hitchhiker's Guide to the Galaxy (2005), on the barren plains of the planet Vogsphere, a massive flyswatter comes up and whacks you in the face every time you get an idea about something (this is used to explain why the Vogons have such flat, stubby noses, and why they have such a conformist, imagination-hating culture). After Arthur Dent, Ford Prefect and Zaphod Beeblebrox have caught onto this, Ford declares "Okay, don't think. Nobody think. No ideas, no theories, no nothing." Beat and then everyone is swatted simultaneously.
- Discussed Trope when some explanation is called for on what the titular inceptions entail. Cobb points out that this trope makes it trivially easy to get someone to think about an idea - but it doesn't mean they will accept the idea, unless you can conceal the fact that you're the one who got them to think it.
- Mal is basically this trope made "flesh" in the dream world; because of Cobb's issues, as soon as she shows up it's very hard for him to get rid of her.
- The "don't think about elephants" bit comes up in Six Degrees of Separation.
- A guy has an impotence problem. One day, late at night, he's sitting in a bar, very drunk and complains about his problem. Then some sleazy guy appears and tells him: "I have some special medicine for you! It costs 1000 bucks, but it'll cure you forever! Just swallow it and wait for five minutes — but remember one thing: You mustn't think of a rhinoceros during that time, or it won't work!" Guess how it turns out.
- A man demonstrates the ability to jump off a tall building and survive, claiming that he can do so by convincing himself he is made of rubber, but then another man splats because he can't help but think of himself as a tomato at the last minute. Cue the actual punchline, from a third person: "Superman, you're a dick."
- Subverted in one of the novels featuring Tiffany Aching, where Granny Weatherwax proudly proclaims that she is "perfectly capable" of not thinking about a pink rhinoceros. Tiffany eventually twigs that this is because Granny doesn't know what a rhinoceros is.
- In the novel Sourcery, travelling inside a magic lamp being held by one of the people travelling, which is moving to its destination because the person holding it is, is possible as long as nobody thinks about the fact it really isn't. One of the characters compares it to "not thinking about purple rhinoceroses".
- In The Light Fantastic, Rincewind and Twoflower hitch a ride on a huge rock which a young druid is flying to an under-construction stone circle. Informed that the rock stays up because the druids have persuaded it to fly, and will fall if anyone's thoughts remind it that rocks can't do that, Rincewind struggles to think of rocks swooping and soaring around rather than sitting on the ground. He's miserably aware that he's not very good at it.
- In Ghost Story, Harry's ghost is told that he can avoid sinking through any surface he "sits" on by not thinking about it too much. Which causes him to immediately fall through the bottom of the car. He does get better at not-thinking later on.
- Five Kingdoms: In Time Jumpers, the plan to lure the torivor Ramarro to Earth via the Pilgrim Path and destroy his powers is hampered by the fact that torivors can read minds. Cole discovers quickly that trying to not think about something is a sure-fire way to end up thinking about exactly that. He ends up getting the help of the only other known torivor, Trillian, to alter his mind so that he believes that if Ramarro goes to Earth, it will not destroy his powers but instead give him dominion over both Earth and the Five Kingdoms. Ultimately, though, Ramarro still sees through the trick, forcing Cole to defeat him in a different way.
- In one Ghosts of Fear Street book (Caution — Aliens at Work), the protagonist temporarily gains Mind Reading abilities. He jokes to his best friend that now he'll finally be able to figure out her Embarrassing Middle Name. Naturally, her first thought is Don't think Priscilla, don't think Priscilla!
- In The Hitchhiker's Guide to the Galaxy Trilogy, the secret of flight is "throwing yourself at the ground and missing and then not thinking about how impossible it is or 'the laws of physics will glance in your direction and demand to know just what the hell you think you're doing' " — in other words, you have to fall and then completely forget about the fact that you're falling before you hit the ground. Then, of course, you can only keep flying as long as you keep forgetting that you should be falling. The books note how difficult this is to pull off in practice. The first time Arthur Dent flies, he's only airborne for less than a minute.
- Discussed and played straight in Hive Mind:
- Played straight: There are several cases where Amber reads somebody's mind and is able to get details about things because the person is actively trying not to think about them.
- Discussed: Amber laments that she can't tell people not to think about things she doesn't want to see in their minds, because it just makes them think about them more strongly.
- In The Hollow Places, the Eldritch Abominations that stalk the willow dimension are attracted to thoughts about Themselves (and, in fact, seem to be able to only "see" thoughts about Them). Unfortunately, knowing that there is a Them you shouldn't think about only makes it harder not to think about Them, particularly when They get close. Kara semi-successfully distracts herself by singing "John Jacob Jingleheimer Schmidt" and dwelling on things that outrage her for most of the book, but the only really reliable way to blank out your thoughts is pain. So her badly injured knee ends up being a good thing. Sort of.
- Near the beginning of the Lensman novel Gray Lensman, this is used to show how well-disciplined Kinnison's mind is — he is able to not think about something he saw in Helmuth's base until he's back on board the flagship. (It was a thought-triggered bomb, so if he hadn't had that mental discipline it would have ended the series early.)
- Lizard Music: Before showing Victor the House of Memory, which gives form to the thoughts and memories of whoever enters, Reynold advises Victor not to think about snakes. This advice results in a giant white cobra appearing inside. Then Reynold tells Victor to think about a corn muffin, and the snake turns into a corn muffin.
- A biography of Tolstoy as a boy that appears in the anthology for children "My Book House" includes an anecdote about Tolstoy and his brother trying not to think of a white bear and then having difficulty thinking of anything else.
- In The Mysterious Benedict Society, the titular society has infiltrated the Learning Institute for the Very Enligthened on Nomansen Island, in order to stop the plans of Mr. Curtain, who wants to use his devious Whisperer device to Take Over the World. As part of their spying, Reynard "Reynie" Muldoon and George "Sticky" Washington are made Messengers, which means they actually get to sit in the Whisperer across from Mr. Curtain and use it to broadcast messages, and also have it soothe their fears. Mr. Curtain has programmed the Whisperer to detect surface thoughts because he knows that fears lurk close to the surface and are easy to detect. When they take their first turns in the Whisperer, Reynie and Sticky try to hide certain stuff, as they're afraid that Mr. Curtain can detect their thoughts. It's fortunate that he can't, as they have no success in hiding them.
"Reynard Muldoon, what do you fear most?" "Spiders," Reynie lied, trying to regain some control. Spiders made Reynie nervous, but he wasn't afraid of them. Certainly they were not what he feared most. That was something he didn't want the Whisperer to know. But responding to Reynie's involuntary answer, the Whisperer said, "Don't worry. You are not alone."
- "Blue Monkey", one of Manly Wade Wellman's vignettes about Silver John. Presented with a supposed magical ritual which the caster announces will only work if nobody in the audience thinks of a blue monkey, John manages not to think about that thing because he focuses all his attention on memorizing every detail of the ritual. Everybody else present finds themselves thinking of blue monkeys, and the ritual fails. Later John reproduces the ritual, carefully avoiding any mention of monkeys and instead telling his audience not to think about a red fish — and it works.
- StarCraft: The Dark Templar Saga: Discussed in Shadow Hunters. Rosemary is being held by a protoss cult and is being mind-probed by her captors, and mentally compares her efforts to keep them out of her head to trying not to think of pink elephants. She then promptly does think of a pink elephants, confusing the protoss for a moment.
- In the Star Wars Expanded Universe, it's not unknown for Jedi to use a leading-questions variant of this trick to make it easier to get information from other people. (Jedi can read minds, but anything deeper than the surface is both difficult and possibly dangerous for both parties.) So for instance, it's hard to simply reach into a guard's mind and rip out the password to a door — but if you ask what the password is, it floats right to the top where it's easy to read. This trick also allows them to learn the names of people who haven't introduced themselves, which helps when a Jedi is aiming to be intimidating. In Legacy of the Force, a factory secretly manufacturing illegal weapons trains its workers to avoid this trick, as they know that Jedi Knight Jacen Solo is coming by for an inspection soon. To their credit, it works well enough, but Jacen still detects that they're hiding something, and instead baits a worker into thinking about where the big secret is located.
- There is a Russian book called The Tale of Hodja Nasreddin (the legendary Nasreddin is a mullah, but here he is described as a mischievous vagabond). In one chapter, he tells the usurer Jafar that he is a powerful (and expensive) healer, but his healing won't work if Jafar or anyone in his family thinks of the red monkey (and he describes it in excruciating detail). His clan spent much of the following night arguing about who was the first to think the forbidden thought.
- Thursday Next: In The Eyre Affair, Thursday's time travelling father shows up and tells her to tell her mother not to paint the bedroom mauve, because she does so in the future and he hates it. Thursday dutifully tells her mother, only to discover that her mother had no plans to paint it at all, let alone mauve; but after Thursday tells her not to, she does.
- Warhammer 40,000 Expanded Universe:
- In Ahriman: Sorcerer, Hemellion knows that the Thousand Sons can read minds. He tries not to think about how much he hates them for enslaving him and destroying his world, only for Sanakht to inform him that he's effectively broadcasting his hatred for all to see.
- In the first Ravenor book, the titular Inquisitor is telepathically interrogating a suspect and asks him about flects. The guy consciously tries not to think about them, which brings everything he knows about flects to the forefront of his mind for Ravenor to read.
- In The 100, when Clarke and Josephine have their Battle in the Center of the Mind, Josephine dares Clarke not to think about where she's hiding all the memories she doesn't want Josephine to find. The door to the room containing said memories promptly opens.
- In Babylon 5, Trakis is "warned" not to think about irrelevant facts such as Adira Tyree's current whereabouts while attending a telepath-monitored negotiation. Of course, that information then appears in Trakis' surface thoughts, where Talia can perceive it without deliberately probing (that being the limit of how far she was willing to bend PsiCorps rules).
- Buffy the Vampire Slayer: When Buffy temporarily gets telepathy in "Earshot", Xander tells himself not to think about sex. It doesn't work. Wesley then lampshades the phenomenon saying "As soon as anyone finds out Buffy can hear thoughts, the first thing they're going to think about is whatever they least want her to hear." As he's laying out the importance of mental discipline and control, he's thinking to himself not to look at Cordelia.
- In the Cyberax arc of Bugs, one of the good guys asks Ros not to think about elephants, to bait her away from Cyberax's thought-activated mental bomb.
- Also invoked in Coupling as the basis to Jeff's "Giggle Loop":
Jeff: Basically, it's like a feedback loop. You're somewhere quiet. There's people. It's a, it's a solemn occasion. A wedding. No, i—it's a minute's silence for someone who's died. Minute's silence, ticking away. *tick, tock, tick, tock* The giggle loop begins. Suddenly, out of nowhere this thought comes into your head: "The worst thing I could possibly do during a minute's silence... is laugh. And as soon as you think that you almost DO laugh. Automatic reaction! But you don't, you control yourself, you're fine. *exhales* ...but then you think about how terrible it would've been if you had laughed out loud in the middle of a minute's silence. And so you nearly do it again, only this time, it's a BIGGER laugh. And then you think how AWFUL this BIGGER laugh would've been, and so you NEARLY laugh again, only this time it's a VERY big laugh. It's an ENORMOUS laugh. Let THIS bastard out, and you get whiplash! And suddenly, you're in the middle of this completely silent room, and your shoulders are going like you're drilling the road! And what do you think of this situation? Oh, dear Christ, you think it's FUNNY!
- Fawlty Towers: In "The Germans" episode Basil tells himself (and others) to not mention the war. He fails miserably, to the point of making one of them cry, after that he does a Silly Walk Hitler impression. To be fair to him, he is badly concussed at the time; even Basil wouldn't be this terrible to his guests under normal circumstances.
Basil Fawlty: Polly, are these German too?
Polly: Oh yes, but I cou—
Basil Fawlty: Right! Right! Here's the plan, I'll stand there and ask them if they want something to drink before the war... Before their lunch! Before their lunch! Do not mention the war!
Basil Fawlty: Ah, wonderful! WUNDERBAR! Ahh! Please allow me to introduce myself, I am the owner of Fawlty Towers. And may I welcome your war... your war... you wall... you all... you all, and hope that your stay will be a happy one. Now, would you like to eat first, or would you like a drink before the war... AHH! Er... trespassers will be tied up with piano wire... SORRY, SORRY!
- One episode of Frasier involved Daphne potentially moving out of Frasier's apartment.
Daphne: Just think, soon I'll be gone and you can have your study back.
Frasier: I wasn't thinking about that.
Daphne: You're thinking about it right now.
Frasier: Well you made me!
- The Mentalist. Jane will often tell a suspect something like "Don't think about where you put the gun" and then watch where the suspect's eyes go (or specifically avoid going, Jane is very good), which tells him where the gun is. Although likely as not it'll be a misdirection, telling Alice this while Bob (the real killer) is in the room, so Bob will look while he thinks Jane is paying attention to Alice.
- Misfits: Nathan has trouble hiding his attraction to Kelly from her Mind Reading powers.
Nathan's Inner Thoughts: Don't think about shagging her. Don't think about shagging her. You're thinking about shagging her. You're an idiot.
- My Name Is Earl. While Earl is in prison he takes a creative writing class, but can't think of anything to write about. His cellmate Sonny is taking the same class and tells him about his story, which involves beating up a gymnast. Earl tries to go into his imagination, but it's a White Void Room with nothing in it but him... and a gymnast. The gymnast offers to be in his story, but Earl declines because "that's Sonny's thing." Earl then spends the next 4 1/2 hours in the room, and the only thing he sees is the gymnast from Sonny's story.
- Defied by Dr. Carson Beckett in the first season finale of Stargate Atlantis. He interrupts somebody trying to tell him how to operate the city's control chair.
Beckett: Don't tell me what not to think about or I'll start thinking about it!
- Pure (2019): Marnie, a sufferer of Pure OCD endures this happening to her when she tries to block out her intrusive thoughts.
- The Twilight Zone (1985): In the episode "Cold Reading", an African doll used as a prop causes everything mentioned in a live 1930s radio serial to come true in the studio — and since it's an adventure show set in Africa, the actors have to be very careful about what they say. They manage successfully until the end, when the announcer says to tune in to next week's show — "Invaders from Mars". Cue spaceship crashing through wall.
- A The Whitest Kids U' Know sketch shows cute animals and a voiceover stating that if you think of various oddly colored animals it will die, then a second later an explosion. Until:
"And this man will die if you think of a cheaper, more efficient way for our nation to use its national resources."
"Or naked women."
- Our Miss Brooks: The episode "Connie Tries To Forget Mr. Boynton" is built on this trope.
- The Ricky Gervais Show: Brought up in a story of when Ricky and Karl met illusionist/mentalist Derren Brown, and Karl was confident that he wouldn't be able to read his mind. Ricky told Derren that if in doubt, Karl will be thinking of monkeys. Derren asked if he was thinking of monkeys, to which Karl replied "I tried not to and I thought of them more."
- Invoked in Final Fantasy X. While on the Farplane, Yuna tells Tidus to think about his father Jecht, and see if he appears, since only those who are dead can show up there as projections. Tidus doesn't want to, because the Awful Truth is Jecht is still alive as the Eldritch Abomination Sin, as Auron already told Tidus in Luca. Tidus notes that "trying not to think about my old man made me think about him, of course."
- In Portal 2, Cave Johnson describes some sort of reaction that would cause the frontal lobe of your brain to become vitrified. Of course, he points out that picturing the reaction causes it, so don't think about it.
- ASDF Movie:
Guy A: Quick, don't think about cats!
[Guy B starts barfing cats]
- 8-Bit Theater: Red Mage proposes a plan which requires the team to build a portable hole the size of the universe, with no materials, twice. Black Mage says it's the dumbest plan he's ever heard. Red Mage says Let's See YOU Do Better! Black Mage says that the plan is so dumb that literally anything else he says would be better. Red Mage points out that the same plan with three universe-sized portable holes would be worse. Black Mage says he won't suggest that, then.
Red Mage: Well, go on, then. Let's hear your idea, smart guy.
Black Mage: All I can think of is the damn three hole version! Argh!
- The page image comes from El Goonish Shive where Diane is in an argument with her imaginary inner child. She states her intention of ending the argument by no longer imagining it. Her inner child demonstrates how pointless this is by telling her not to imagine an elephant.
- In Freefall, Sam gets the robots to think up a devious master plan for him this way:
Sawtooth: All we have to do is not think of a devious master plan for Sam.
Dvorak: You didn't.
Qwerty: Oh, come on! It's like being told not to think of a rhinoceros with a teacup.
- Grrl Power combines this with some magnificent trolling; a sign in the men's shower room that reads, "Try not to think about the fact that some of the most beautiful women on Earth are showering, changing and possibly having tickle fights on the other side of this wall." (One of the guys has a tendency to bug his teammates with questions about the odds of that type of stuff actually happening; he thinks the sign maker is an "evil, evil genius.")
- Manly Guys Doing Manly Things: Time travel technology only works if you don't think about it. Time travel veterans make a point of distracting first-timers so the trip goes smoothly.
Commander Badass: Yeah, time travel's been super stable ever since scientists figured out that th' less ya think about it th' more solid and seamless everything hooks up. S'like they say, "A watched cheetah never bevels."
Jones: That is not a thing people say. What does that even mean? Literally no person has ever said that befo—
[suddenly, they're both in the future]
Commander: 'S way more efficient than saying "Don't think about time travel."
- Oglaf: In "The Fortress of the Prude King", a tentacled monster tells a man not to think about it while masturbating. He promises not to... and is none too happy, and unaroused, when this makes him think about the ugly monster the next time he's doing it.
- A variant in Questionable Content, when Dora is stricken with an unwelcome mental image of her brother having sex with Faye. Faye hurriedly tells her to think of purple elephants. Dora then laments that she can now only imagine a purple elephant having sex with Faye, declaring that everything is ruined forever.
- xkcd in the Tongue Awareness Month strip.
- The Game. An internet fad that uses this trope as its premise: You lost The Game when you think about it. So it's popular to see someone in the internet saying "you lost The Game" or just "The Game" to make someone lose. This, of course, also means that they lost too, since one must think about The Game in order to write about The Game. Basically, Failure Is the Only Option. It's generally accepted you have a while to forget thinking about it, such as 5 minutes.
- Mama Mathers in Ward exploits this with her power: if you see her and later think of her, she can read your mind. Not only that, while she's reading your mind, images of her appear in your head, so it's almost impossible to get her out. Rain Frazier tries to avoid thinking of her so she won't find out about his friends or what they know, but he fails when a friend mentions possibly being watched.
- The You Laugh, You Lose! game. The idea is you're not supposed to laugh, no matter what bizarre nonsense is happening in front of you, so of course it's ten times harder not to laugh.
- In the Darkwing Duck episode "Heavy Mental", there's an invention that give normal people assorted Psychic Powers. However, the targeted person isn't supposed to be thinking at all while the invention is used on them, or else their head will explode. Guess how the Villain of the Week is defeated.
- In the Dragon Tales episode "Roller Coaster Dragon", Wheezie is impatient at the ten-minute wait for the roller coaster dragon and starts driving everyone nuts with her constant questioning of if it's time yet and otherwise chattering about how she can't stand the wait. Eventually, she declares that she just won't think about it and starts chanting "I will not think about the roller coaster dragon," before admitting that thinking about not thinking about it isn't working.
- One of the Couch Gags of The Grim Adventures of Billy & Mandy invokes this trope, as Mandy appears dressed up as a polar bear and tells the audience "Don't think about polar bears."
- In the Johnny Bravo episode "In Your Dreams", Johnny, inside of a dream, is on a date. After learning from the real world that anything he thinks of will happen in the dream world, his date randomly tells him to not think of her as a one-eyed, tentacled sea monster. Naturally, he has to then picture her as one, which turns her into one.
- Referenced in the Justice League Unlimited episode "The Ties That Bind". After the heroes pull a fast one on Granny Goodness, mind-reader J'onn tells her to try not to think about where she's keeping her hostage. Granny cringes, and J'onn promptly gives Flash his location.
- Happens in a first season episode of Men in Black: The Series. K had been infiltrating a psychic alien conspiracy that has been trying to invade earth for years. K disguises himself as one of their own (who had willingly let him do so because he had gone native). After explaining everything to J, this happens:
K: Oh. And whatever you do, don't think about what I just told you.
J: That's the last thing you tell someone when you don't want them to think about something!
[they are then immediately caught]
- This is the main principle behind a polygraph test—unlike a Hollywood Lie Detector, the goal of a polygraph isn't to catch the subject in a lie, but rather to force them to think about the incident or suspected act through questioning them, with the idea being that if they are culpable or downright guilty, they would have a stronger reaction to thinking about it than someone who is not involved, and this reaction would be shown in the polygraph's readings. Of course, the process is far from perfect; if a subject is particularly nervous or otherwise affected by the incident (for instance, if the subject was close to the victim or had a past traumatic experience with an incident of similar nature), it can read a false positive during questioning. Likewise, a subject who is guilty but is able to suppress their reaction to the questioning or is not sensitive to the fact that they are guilty can "pass" a polygraph test with no trouble. As a result, polygraphs are rarely if ever used as admissible evidence in court, and typically only used in situations to pressure a suspect into confessing, or to obtain a "reasonable cause" for law enforcement to continue their investigation.