When someone or a group of people come across a written magic spell, or a magical-looking item (like a Spell Book, enchanted toy, amulets etc), they then try to play pretend magic with it, thinking that it's not something really magical. What Could Possibly Go Wrong?
And then it happens: the incantations and rituals they did are Real After All!
They may then discover it and maybe try actually using it for practical purposes. If they are lucky, it's just a normal magic spell or item. If they aren't, it's one that spells doom, either to themselves or somebody else or worse, everyone. Can get particularly odd when the magic stuff actually warn you of the dangers of doing magical things with it.
Contrast "Sorcerer's Apprentice" Plot when the character knows something really is magical but doesn't realize the potential danger (and then gets scolded by their mentor). Contrast Magic Misfire, where the caster is serious about trying to cast magic, but messes it up. Compare and contrast Real After All, which is when the "real thing" only shows up at the end when everyone thought the thing in question was a fake. See also Idiot Ball, Schmuck Bait, and And You Thought It Was a Game. Can overlap with Evil Is Not a Toy and Genre Blind.
- Death Note: Light initially thinks the Death Note is somebody's twisted idea of a prank. It's only after he tests it on two people (a man holding a classroom hostage, and a sexual harasser) that he's sure it's the real deal.
- The French comic Dies Irae starts with a teenager finding a magic book in an old house. The first thing he tries is a succubus-summoning spell with modern ingredients (a mermaid Barbie's hand works as well as the real thing, Coca-Cola for vulture's blood, etc.). To his great surprise, it works, so he then tries a good-luck charm, but it seems to work by inflicting horrible accidents on others. As a more competent demonologist later explains to him, the disasters were actually the succubus' doing, since he allowed her out of the circle when they first met in order to bang her.
- In one of the Hellblazer comics, John prevents his niece from casting a dangerous revenge spell on another girl. It turns out she got the spell from an amateur who's thrilled a magician of John's caliber would pay attention to him, having no idea of what kind of powers would be attracted by that curse. John... sets the record straight, and tries make sure Gemma knows not to get involved in black magic.
- One of the stories in the original Men in Black comic was about a group of kids playing a Dungeons And Dragons clone who found an ancient mystical artifact and used it as their 20-sider. (They didn't know it was magic, they just thought it was cool-looking.) When one of them casts a "summon demon" spell, an actual demon appeared and destroyed half their house, and most of the town they lived in.
- Played with and ultimately subverted in Ms. Marvel (2014). When some of Kamala's friends think they need to summon Loki, who they refer to as "hipster Viking dude," they try a ludicrously made-up ritual using hipster iconography. Loki does eventually show up, not because the ritual worked, but because he couldn't stand how silly it all was anymore. He even brought popcorn.
- Hocus Pocus: When Allison takes Dani and Max to the witches museum on Halloween showing them the Sanderson Sinsters' home and possessions, including the Black Flame Candle, which will bring them back to life for one night when lit by a virgin on All Hallows Eve, Max, who happens to be a virgin, sarcastically suggests lighting it and meeting them. After being attacked by Binx the cat, the girls want to leave, but Max dismisses it all as "a bunch of hocus pocus" and lights the candle. The flame turns black and the witches come back. Hilarity Ensues.
- Knights of Badassdom: The LARP-party's wizard bought a creepy old tome off the internet to add to his get-up and accidentally used it to summon a real succubus from hell.
- In The Evil Dead (1981) they accidentally summon the evil dead by jokingly reading out from The Book of the Dead.
- The Shaggy Dog In the original version, Wilby Daniels finds a ring with a Latin inscription in it: "In Canis corpore transmuto." He likes the sound of it and sings it to himself several times while holding the ring. Then he turns into a dog.
- The Craft: Teenage girls form a witch's coven, seemingly just as a counterculture act. But the rituals they perform end up having real magical effects.
- The Gate: Some boys find a record with a recording of a demonic chant. They think it's amusing, and play the record. The chant actually opens up a Hell Gate.
- In Sherlock Holmes, the villain Blackwood passes himself off as a talented magician. His spells turn out to be tricks, but Holmes notes that Blackwood performed all the magic rituals perfectly, which could mean "the devil's due a soul". Sure enough, there's a conspicuous raven following Blackwood around everywhere he goes...
- The Mummy (1999): Evy has no idea that reading from the book she's just found will release Imhotep.
- The premise of Ouija is that a bunch of kids play a Ouija Board as a joke, only for it to turn out to really summon spirits, causing all types of wacky hijinks.
- The Disney movie Bedknobs and Broomsticks has a reversed example. Miss Price is a spinster who enrolled for mail-order witchcraft lessons so she can use the mailed spells to aid Britain's war efforts during WWII. However she receives a letter informing her that the remaining classes were canceled, just before she gets the one spell she really needs. She (along with some children assigned to her care) travel to London via a enchanted teleporting bed to confront Mr.Brown, the administrator of the classes, so she can get that spell. However it turns out that Mr.Brown is a fraud, who doesn't think magic actually exists and was just selling transcripts of the spells he found in an incomplete 'spellbook', hoping that gullible individuals will pay for 'fake' magic spells from a faraway 'headmaster' they've never met. The idea that the spells would actually work for anyone, such as Miss Price, never occurred to him to be an actual possibility. After being convinced of the existence of magic by a temporary bout of Baleful Polymorph, much of the plot afterwards is for the group to search for the other half of Brown's spellbook for clues for the one spell Miss Price seeks.
- Prince of Darkness: One of the main signs things are starting to go to hell in the church the film is set in is when the amateur magician of the group, constantly trying the simple trick of making a card "disappear", accidentally does something that makes the card genuinely disappear from existence.
- In the final Narnia book The Last Battle, the false prophets do a ritual to summon the Calormen God of Evil Tash, for a stunt with which to kill anyone they deem troublesome. But it's Gone Horribly Right, as Tash actually does turn up and wreak havoc among there.
- In The Light Fantastic, the hitherto incompetent wizard Rincewind, pursued by a mob intent on wreaking revenge on all things wizardly, throws his usual desperate bluff to gain time. Rincewind's tactic in a fight is to strike the pose of a wizard about to cast a lethal spell, knowing Genre Savvy pursuers will realize exactly what it means when a Wizard strikes a pose with arms extended and fingers poised to deliver death. It usually buys Rincewind enough time to run and get away, or else to do the unexpected and deliver a more mundane punch or kick. But to his surprise, for the very first time the magic ignites, his fingers crackle with octarine fire, and people get killed. He just wasn't expecting this.
- In Eric, the titular amateur demonologist believes Rincewind to be a summoned demon and orders him to grant his wishes. Rincewind sarcastically asks if Eric thinks that happens with a snap of Rincewind's fingers... and they find themselves deep in the jungle. Rincewind looks at his fingers with deep suspicion after that. There's a demon lord casting all the magic when Rincewind snaps his fingers, all part of a complex plot to overthrow the current king of Hell.
- Lords and Ladies The young witches are "new age Wiccan"-type witches, all about mystic symbolism and occult jewelry, while the old witches know that real magic is mostly psychological and comes from not being used. The girls actually have magic power, but it's being supplied by an elf queen in order to help their invasion of the disc.
- The Diana Tregarde novel Burning Water has a flashback to when Diana and Mark first met. Mark and three of his buddies held a seance on Halloween because one of his buddies was studying anthropology and was curious about whether there could be anything to those old rituals. They were trying to call up Julius Caesar, they got a demon instead, and Diana had to interrupt studying for her midterms to keep the demon from possessing Mark.
- This is the premise of Pamela Dean's The Secret Country trilogy, in which five young cousins who pretend to be characters in a fantasy world end up crawling through a bush and find themselves trapped in that fantasy world. It's ultimately subverted, though, with The Reveal that the idea of the Secret Country was magically planted in their heads by a magic-user from the Country, in order to get them to come to the Country; they never made it up at all.
- The Laundry Series notes that this can happen to people who take H. P. Lovecraft too seriously. When CASE NIGHTMARE GREEN gets going, any kind of ritual could do this.
- A short story called The Gazing Ball has a very benign example—a little girl's father buys a new home with a garden—within this garden is a faerie garden for her, complete with gazing ball. When she looks in the ball, she expects to see herself—but sees a fox-like creature, who likewise didn't expect to see a human girl in his gazing ball. The two begin a VERY long-distance friendship that takes an unexpected turn when their respective worlds make contact. Alas, by the time it's possible for their people to easily travel from one planet to another, a century has passed since the two first made contact, which means they are far too old to make the trip, and never see each other face-to-face.
- The H. G. Wells short story The Man Who Could Work Miracles centers on one George Fotheringay, a nondescript fellow who's been both unremarkable and a skeptic into his thirties. While debating with comrades at a bar, Fotheringay commands a table candle to levitate inverted, and its flame burn downwards as well. To everyone's astonishment, the candle and flame do precisely that. His sudden Reality Warper powers unnerve Fotheringay, though he later conducts further trials of his newfound powers.
- Magic by the Lake by Edward Eager has this happen at the end of the first chapter:
"Magic by the lake," said Martha, trying out the words to herself. "Doesn't it sound lovely? Don't you wish it were true?""I certainly do," said Jane.There was a silence. The turtle stuck its head out of its shell."Now you've done it," it said.
- In a Noodle Incident from The Anubis Gates, a group of dabbling amateur spiritualists were holding a Spooky Séance near one of the time gateways when it opened up. Proximity to such open gateways causes magic, most of which has long since faded from the world, to become locally functional again. This is implied to be why the seance's participants - none of whom were prepared for a successful outcome - were all found dead the next morning, with looks of shock and horror about what they had summoned on their faces.
- Are You Afraid of the Dark?. In the episode "Jake and the Leprechaun", a play in which the protagonist's character is turned into an elf turns out to be a real ritual which will subject him to a Baleful Polymorph and give the villain his lifeforce.
- Supernatural. A symbol from a theology textbook used in a prank, and accidentally activated turning the prank ghost real.
- In the episode Bloody Mary the eponymous murderous ghost is summoned by characters chanting her name in front of a mirror without believing the urban legend.
- Fred accidentally got transported to Pylia after reading some words out of what turned out to be a magical spell book.
- Angel interrupts some Wolfram & Hart mooks preparing a ritual which they don't know what it's for. They're just following the recipe their supervisors gave them.
- There's an episode of Xena: Warrior Princess where Gabrielle corrects someone's reading of a spell (they were using the wrong meter) and Gabrielle accidentally summons three Titans.
- An episode of Weird Science involved Lisa encountering a strange man who seems to able to detect that something is not normal about her. By episode's end, the man is revealed to really have magical powers. What's weird about that, considering Lisa has magical powers? Well Lisa's "powers" are due to her being a computer generated program... The man on the other hand....
- One episode of Charmed had three lonely depressed college girls attempting to perform a spell on 3 animals that turns them into attractive men. To their surprise, the spell works.
- Warhammer Fantasy Roleplay story hook, some children steal a bunch of notes from a scholar on a dare, and upon seeing it contains some weird funny notes and symbols, decide to "play magic". Unfortunately, it is a summoning ritual for an ancient Chaos warrior that was buried alive in this place...
- Macbeth One of the reasons this is known as The Scottish Play is because it used "real" witchcraft chants (which King James, a notable believer in witchcraftnote , decreed should only be spoken during a performance, just in case).
- Doctor Faustus Inverted when John Faustus recites a conjuring spell he is given, so when the messenger to the Devil appears, Faustus thinks that it has somehow worked. The demon tells him that it didn't work, but he was listening anyway and decided to find out what Faustus was doing, especially because Faustus was blaspheming and the demon really likes that.
- Fable II. One of the side-quests involves fighting an army of Hollow Men unwittingly summoned by a pair of idiots with a spellbook.
- Appears frequently in the Shin Megami Tensei: Persona series:
- In Persona, the protagonists gain their powers by playing the Persona Game, a Bloody Mary-like ritual which several of them complain is just superstition.
- In Persona 2, the protagonists participate in a similarly-mocked ritual involving dialing your own cell phone number, and are targeted by Joker as a result.
- In Persona 4, the protagonist discovers his power to enter TV sets after begrudgingly trying out an Urban Legend involving staring into a powered-off TV on a rainy midnight.
- In Corpse Party Blood Covered the main characters perform a spell named Sachiko Ever After. Not only does this spell actually work, but it also works in a completely different way than they first thought.
- Legendary: The Box opens with thief Charles Deckard opening the item he was hired to steal, Pandora's Box, unaware of its true nature. This unleashes all manner of mythological beasts and grants him the magical power of the Signet.
- CLANNAD: Main character tries out a book of charms out of boredom in his visits to Yukine's old library reference room. There are nontrivial instructions like "stack two coins on edge, then say the written words, then think of someone" with promised effects written out. Realizing a pinch of Literal Genie at play later, he's led to believe that it's the spell that has caused him to get locked with Kyou in a sports equipment shed, so he has to perform some embarrassing actions to dispel the charm. In the visual novel, certain choices lead to scenes with other characters in place of Kyou (even Nagisa's dad).
- Many versions of the Horror Movie Survival Guide can be found on the Net. Some of the examples of advice that apply to this trope:
- Never read a book of demon summoning or other evil book aloud, even as a joke.
- Do not allow children to read old books unsupervised.
- Ancient Satanic spells should never be chanted unless it's a dire emergency.
- SCP Foundation, SCP-717 ("The Ambassador"). SCP-717 is the ruins of a home where a cult once worshipped. A group of teenagers tried to use a Ouija Board in the basement and opened a gate to another dimension, which allowed a group of spirit entities to enter the basement and attack them.
- Unsong: Chapter 8:
Thirty years ago, when the sky cracked, the assortment of hermeticists, Wiccans, and uncool teenagers practicing magic noticed that their spells were starting to actually work. Never unambiguously. But the perfectly possible things they asked of their magic were starting to happen more often than chance. Of course they ran around telling everybody, and some people did controlled experiments, and finally people started to believe them. A hundred different schools of witches and warlocks went around curing people's illnesses and blessing sea voyages and helping people find their true loves.
- Justice League Unlimited, one episode starts with a bunch of frat boys performing a necromantic ritual for fun. Unknown to them (until he came crashing through their door), the ritual revived a recently-Killed Off for Real Solomon Grundy and boosted his power to the point even Amazo can't stop him.
- Jackie Chan Adventures, Jade draws the Mark of Tarakudo on her ankle as a fake tattoo. It became a more permanent Power Tattoo which granted her control over the Shadow Kahn and corrupted her into becoming Queen of the Shadow Kahn until it was removed, of course.
- In one Scooby-Doo episode, Shaggy and Scooby find a spell book and read a couple of spells from it, finding them ridiculous. What they don't know is that the spells have turned them into monsters and then back to normal without them ever realizing it.
- In the Bugs Bunny cartoon "Transylvania 6-5000", Bugs spends the night at the castle of Count Bloodcount, a vampire wanting to sink his fangs on our hero. Unable to sleep, Bugs picks up a book on magic spells and reads out loud about the words Abracadabra and Hocus Pocus. Unknown to him, those words cause the Count to turn into a bat and back again, respectively. As Bugs makes up a song about them, the Count keeps changing at the most inopportune times.
- In the South Park episode "Hell on Earth 2006", a running joke throughout the episode is various characters being dared into summoning Biggie Smalls in a Bloody Mary-type ritual. Most end up chickening out and defending their actions by saying it's not real, only to try later when they're alone and succeed in summoning Biggie.
- In Captain Underpants: The First Epic Movie, to avoid being punished by Principal Krupp, George and Harold wave a toy ring around claiming that's it's a mind control ring in a desperate, last-ditch attempt to intimidate Krupp. What they don't know is that the "toy" is not a toy at all, but an actual mind control ring, and they actually succeed at controlling Krupp's mind, creating the Captain Underpants persona and thus setting the plot of the movie in motion.
- In The Simpsons, Tree House of Horror episode "Dial 'Z' for Zombie", Bart discovers a book of spells. To test it out he offers Lisa to use it to bring Snowball I back from the dead. The spell Goes Horribly Wrong as it causes zombies to rise from the grave all over the world.