-> '''Question''': Can we use "Go Up A Level" cards on other players to make them fight a monster that would otherwise ignore them?\\
'''Answer''': We want to say no, but that's just such a Munchkin thing to do that we have to allow it.
-->-- ''TabletopGame/{{Munchkin}}'' FAQ

The aversion of the control the developers have on the players. Basically, the player finds ways to play the game that the developers and designers did not intend.

Usually a GameBreaker, it often leads to GameplayDerailment, but not always: in some cases, it can become an AscendedGlitch, or is considered "fair" in some way (for example, the intended use is (at least) just as useful, and there exists some limit on how frequently you can use the unintended mechanic (see, for example, Time Outs in Sports, below)).

In TabletopGames, the discovery of a GameBreaker via Not The Intended Use usually leads to the ObviousRulePatch, especially in tournament-level play.

Often used by {{speed run}}ners and other [[ChallengeGamer Challenge Gamers]]. When it's an actual software ''glitch'' that's exploited, it belongs under GoodBadBugs.

Subtrope of EmergentGameplay. See also: WeaponizedExhaust, RecoilBoost. Contrast UselessUsefulSpell and MundaneUtility. Also contrast FakeDifficulty, caused by control or other design problems. When an element is ''intentionally'' fudged in the player's favor, it's an AntiFrustrationFeature.
* NotTheIntendedUse/VideoGames


[[folder:Anime and Manga]]

* ''Manga/FateKaleidLinerPrismaIllya'': Counter Guardians are entities meant to protect humanity. After gaining the power of one through [[spoiler:the Archer Card]], [[spoiler:Shirou]] decides to use it for the sake of saving a single person, knowing very well that his actions are detrimental to humanity and go against the purpose of what said-power was intended for.
* Part of the fun of ''LightNovel/Overlord2012'' is seeing typical fantasy spells used in creative ways. One early example is Ainz providing two Summon Goblin Army scrolls to a village he'd taken a shine to, to protect them from attacks once he left. Once he was gone, the girl he provided them to used them while there were no enemies around at all... and had the army [[TrainingThePeacefulVillagers teach the villagers to defend themselves]] and assist in designing and building fortifications.
* ''Anime/SwordArtOnline'' has Outside System Skills, abilities that weren't programmed into the game that players created for themselves. The most well-known and oft-used of these is "[[SwitchOutMove Switch]]", where one player attacks with a Sword Skill, then an ally attacks the offset opponent with a Sword Skill of their own while the first attacker recovers.
* In chapter 4 of ''Manga/GoblinSlayer'', Goblin Slayer uses the Priestess' protection spell [[spoiler:to prevent a bunch of goblins from escaping the massive fire Goblin Slayer started.]] The Priestess herself is disturbed by the tactic.

[[folder:Card Games]]
* ''TabletopGame/{{Dominion}}'' has the Chapel card; intended to get rid of hurtful curse cards, people realized it could be used to streamline your deck by trashing the low-value cards you start with. [[FollowTheLeader Later deckbuilding games]] such as ''Puzzle Strike'' and ''Ascension'' [[AscendedGlitch use this as an intentional design choice]], so removing your own cards from the deck for greater efficiency is now expected. ''Ascension'' doesn't even ''have'' any harmful cards to remove.
* The [[Tabletopgame/YuGiOh Yu-Gi-Oh! card game]] has more than a few instances of this too:
** Barrel Behind the Door was initially meant to bounce back damage done to you by effects. It works just as well bouncing non-cost damage from your cards to your opponent. It was even released in the same set as Ring of Destruction, a card that does massive amounts of damage to you and your opponent; the Ring/Barrel combo swiftly became one of the most popular in the game.
** Using Doomcaliber Knight's ability to negate your own effect, which destroys him... so you can summon a quite powerful Meklord Emperor.
** Gate Guardian is a high-ATK monster that's incredibly hard to get out... but you don't need to get him on the field to fuse him with a card released much later, [=UFOroid=], to form an even stronger [=UFOroid=] Fighter.
** [[http://yugioh.wikia.com/wiki/Royal_Oppression Royal Oppression]] was designed to be used as an anti-meta card to cripple meta decks reliant on special summoning. But then players began to realize that they could swarm the field with big monsters and then activate it during the opponent's turn to lock them out from their own special summons. This ultimately resulted in it getting banned.
** There are quite a few cards that operate at the cost of letting your opponent draw cards. Since you instantly lose if your deck runs dry some savvy players built decks ''entirely'' out of these cards, using their intended effects as defense while they bled their opponent of all his resources.
** Divine Sword - Phoenix Blade is a subpar Equip Card, exclusive to Warriors, that provides a miniscule ATK boost. However, it was also a staple in one of the most popular Decks of its day, Diamond Dude Turbo, for its secondary effect of "remove two Warriors in your Graveyard from play to add this card back to your hand." Players would use Phoenix Blade's secondary effect over and over, then activate Dimension Fusion to resummon all the cards they removed.
** Which players are the biggest users of Toon Table of Contents, a card that lets you search out any card with "Toon" in its name? If you guessed Toon players, you'd be wrong - Toon Table of Contents is used in nearly all modern Exodia Decks. This is because you can use Toon Table of Contents to search out copies of itself, and there's no limit to how often it can be used. That translates to three cards removed from your Deck, and three Spell Counters on Royal Magical Library... and you can then either search out Toon World for a fourth counter, or Blue-Eyes Toon Dragon to discard for Trade-In. Toon Table of Contents is actually straight-up better than Gather Your Mind, a card where this use ''is'' the intended use.
** This is what got Self-Destruct Button (a card that forces the Duel to a draw if your opponent has 7000 more LP than you) banned. Instead of using it as a last-resort TakingYouWithMe, players would fill their decks with cards that gave your opponent LP, then activate Self-Destruct Button at the first possible opportunity.
** Last Turn is meant to be an extreme last-resort gamble: it can only be used when your LP are 1000 or less. It picks a monster on your side of the field, then sends everything else to the Graveyard, then your opponent Summons something from their Deck and attacks, with the survivor winning the Duel. The gamble involved was the risk that your opponent could Summon something stronger. However, Last Turn ignored the possibility of cards that could stop the Special Summon in some manner (see Jowgen the Spiritualist, Vanity's Fiend, Last Warrior from Another Planet) and the existence of cards that could pay massive amounts of LP (Wall of Revealing Light, Inspection, Backs to the Wall). If the opponent couldn't Summon a monster for Last Turn, you won by default. The resulting "Last Turn OTK" sent Last Turn to the banlist.
* TabletopGame/{{Munchkin}} allows you to use "Go Up A Level" cards ''on your opponent'' in order to force them to fight/run away from a monster that would ignore them if they were just one level lower.
** The creators of the game were asked if the cards could be used that way--while that hadn't been the intent, the creators responded it was such a Munchkinly thing to do, they just couldn't say no.
* ''[[TabletopGame/{{Pokemon}} Pokémon Trading Card Game]]'':
** Claydol's "Cosmic Power" is meant to draw cards from the deck, but its secondary effect, putting 2 cards back to the bottom of the deck, can also be used to prevent a player from running out of cards in one's deck and thus avert a loss by decking out.
** The trainer card Gamble can be used the same way, though somewhat more risky. You shuffle your hand into your deck and flip a coin. Draw 7 for heads, 1 for tails.
** The Mysterious Fossil card was intended to be used as the fossils in the [[VideoGame/PokemonRedAndBlue original Game Boy games]], as a method of acquiring Kabuto, Omanyte, or Aerodactyl. However, the mechanic allowing it to be your Active Pokemon yet not permit a Prize draw when your opponent KO'd it meant that many players used it as a cheap wall while they set up their actual Pokemon. [[ObviousRulePatch Future Fossil cards did not work this way]].
* In ''MagicTheGathering'', many combo decks (and subsequently, card bannings or errata) come from this sort of behavior. Although one can debate over which examples qualify as "not intended" vs simply "not ''obvious''"; the developers do fully ''intend'' for players to come up with card combinations they didn't see themselves and simply hope that they won't miss any that break the game, while in some cases they're aware of the unorthodox use and go ahead anyway. Examples include:
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=121155 Dark Depths]] and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=192232 Vampire Hexmage]]: The Hexmage was meant to remove beneficial counters from permanents and as a way for black to deal with planeswalkers. But with Dark Depths, you can remove all the counters to get a 20/20 flying indestructible creature on turn 3.
** Cascade cards and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=113533 Hypergenesis]]: You're supposed to suspend Hypergenesis, but cascade lets you search it out of your deck and cast it for free. This also works with other cards with no mana cost, such as [[http://gatherer.wizards.com/Pages/Card/Details.aspx?name=living+end Living End]].
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=287335 Grove of the Burnwillows]] and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=247550 Punishing Fire]]: The Grove is supposed to be a dual land that fights against red and green's aggressive nature, but it lets you get back Punishing Fire instead.
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=3255 Lion's Eye Diamond]]: Intended to be a bad Black Lotus, instead you can toss your hand into your graveyard as a beneficial effect for [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=5629 Yawgmoth's Will]] (often used while a tutor for Yawgmoth's Will (or Yawgmoth's Will itself) is on the stack, doubly stupid because you can then recast it from the graveyard and get more mana with no drawback whatsoever), dredge cards, or madness cards. Another extremely powerful trick with it is to use it while a draw-7 spell (which generally cause you to discard your hand and draw a new one) is on the stack, so that it again has no drawback, or while a reanimation spell which does not need to declare a target is being cast, so as to put the card in question into your graveyard for ready reanimation.
** Wizards of the Coast is infamously bad at making a "bad" Black Lotus; [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=194975 Lotus Petal]], a Black Lotus which only produced one mana instead of three, came out shortly thereafter, and was restricted shortly thereafter. When they made [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=370562 Lotus Bloom]] later on (a black lotus which took three turns to come into play), it yet again caused problems by allowing [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=370537 Dragonstorm]] decks (itself a previous JunkRare, reprinted because it was theoretically a bad storm card due to costing too much mana) to get a bunch of extra spells cast on the fourth turn for free. Combined with [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=121217 Rite of Flame]] and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=243487 Seething Song]] (attempts to create "fair" [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=373329 Dark Ritual]]s), along with [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=96864 Gigadrowse]], a card intended for limited but actually useful for tapping all of your opponent's lands during their endstep to prevent them from interfering with your plans (and nearly uncounterable due to its own ability to replicate itself into multiple spells), the deck created a rather terrifyingly powerful combo deck which regularly "went off" on turn four and instantly killed the opponent via [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=243464 Bogardan Hellkites]].
** Another "bad" Lotus attempt was [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=4593 Lotus Vale]], which required you to sacrifice two lands in order to keep it with the end result of getting three mana out of one land. Unfortunately, how it was initially worded caused it to be able to tap for mana in response to its own sacrifice requirement, making it essentially a one-a-turn Black Lotus. This was errataed, however, and no longer works that way.
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=159749 Illusions of Grandeur]] and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=15168 Donate]]: Two quirky {{junk rare}}s for casual players that combined to become one of the most famous kill conditions in the competitive ''Magic'' history. It didn't help that Illusions of Grandeur has the text "gain 20 life" on it, which, with [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=194977 Necropotence]] in play, reads an awful lot like "draw 20 cards".
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=5833 Waylay]]: Meant as a way to get temporary blockers, but a rules change made it into "White Lightning," a way to get hasty attackers for a turn. It was errated to only work as intended.
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=3337 Flash]]: Meant as a way to play creatures at times you're normally not allowed to, it does this by letting you put a creature card from your hand into play, but you have to sacrifice it unless you pay its mana cost reduced by 2 (where 2 is the cost of Flash itself). What this ''actually'' means is that for 2 mana you can get the "when this comes into play" and/or "when this dies" effect of an arbitrarily expensive creature, some of which are powerful enough to instantly win the game with the right support. It was errata'd the first time this abuse was discovered with [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=15138 Academy Rector]], then un-errata'd due to a policy change to minimize the use of errata, and promptly banned or restricted in all the formats it was still legal in thanks to an instant-win combo with [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=107598 Protean Hulk]].
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=201122 Boomerang]] existed for years as a cheap and fairly versatile blue bounce spell; it seemed fair enough, so printing a worse version in [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=79155 Eye of Nowhere]] seemed safe enough. At the same time, the long-time classic [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=247316 Howling Mine]] was in print, a card which historically was sometimes used with artifact tapping abilities to give card advantage, but was typically viewed as a weak combo piece. [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=84364 Kami of the Crescent Moon]] was a generally worse Howling Mine, a weak creature which could blow low-powered creatures but which was fairly easily killed. While alone, some of these cards were alright, in concert, combined with more powerful delaying cards like [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=380255 Remand]] and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=84065 Exhaustion]], both of which also helped to keep the opponent's hand full without letting them actually play any spells, the deck would rather quickly bounce the opponent's ''lands'' back into their hand while preventing them from casting any spells, putting various card draw spells into play which would cause the opponent to draw so many cards that they had to discard the excess cards, something which almost never happens in tournament play. Worse still, [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=88799 Ebony Owl Netsuke]] and [[http://gatherer.wizards.com/pages/Card/Details.aspx?multiverseid=129750 Sudden Impact]] had been printed as a means of punishing decks which took advantage of the Kamigawa block mechanic which encouraged players to keep their hands full, a nearly useless mechanic due to the fact that it meant that the player wasn't casting spells, and as such, spells designed to punish cards that no one ever used were pretty useless. But in this deck, it simply punished absolutely everyone for daring to sit down at the table. A very powerful deck, it was quite good at completely destroying control decks, but had absolutely no ability to win games against aggressive decks which played lots of cheap, powerful creatures and burn spells, which the deck only gave further fuel to.
** Another example from the same time period was the Eminent Domain deck, so-named because it used [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=84564 Annex]], [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=88945 Dream Leash]], and [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=83037 Confiscate]] to steal their opponent's lands, [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=249384 Icy Manipulator]] to hold creatures at bay and tap down more lands, [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=83281 Stone Rain]] to destroy what lands it couldn't steal, and finally [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=83483 Wildfire]] to destroy all of the lands the opponent had left, along with whatever creatures they'd managed to play, while leaving them with excess lands due to their own stealing and artifact mana, which was untouched by the wildfire; if the opponent DID manage to cast some good creature, then they'd just steal it with Dream Leash or Confiscate themselves. While Wildfire was known to be a very powerful card, Annex had been thought of as a means of punishing players for playing certain kinds of lands, not as a means of allowing a player to steal their opponent's lands and cast a wildfire with a two-land advantage, possibly as early as turn four. The sheer number of permanent stealing spells made the deck extremely versatile, as it could steal anything the opponent used to fight with - lands if they needed mana to cast powerful cards, creatures if they were a threat, and even valuable artifacts - and set the world on fire with a huge advantage on its side. As a result, land-stealing spells became much harder to come by afterwards.
** Even some of the official [=WotC=] staff have gotten in on this. Back before he became Rules Manager and thus [[DefectorFromDecadence devoted himself to curtailing this sort of madness]] (whether or not this is a good thing depends on your perspective), Mark Gottlieb ran the House of Cards, a weekly column devoted to creating insane decks and combos, the most infamous of which was turning a [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=49026 subpar creature-producing artifact]] into a [[http://archive.wizards.com/Magic/Magazine/Article.aspx?x=mtgcom/daily/mg108 repeatable board-clearing engine of destruction.]] He even paraphrases the trope's name when describing the combo!
** [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=397443 Grindstone]] was an artifact from ''Tempest'' that discarded the top two cards from a player's library, and repeated the process if their colors matched[[note]]A third of the average deck is lands, which are colorless. Getting even one of these as the two milled cards stopped it from repeating, as it only works if both share a color, and "colorless" isn't a color. Needless to say, getting more than one repetition was rare.[[/note]]. It was considered a JunkRare and was quickly forgotten. Over ten years later, Shadowmoor came out and had a "color matters" sub theme, so they printed [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=146022 Painter's Servant]], which made all cards in the game count as any of the five colors. When the two are played together, you can destroy your opponent's entire deck on turn 3. [[/folder]]

* Invoked InUniverse in ''Disney/WreckItRalph''. [[spoiler: Vanellope's glitching can be exploited to pass other racers, which quickly makes her the most popular character after Turbo is defeated and she becomes a playable character.]]
* In the ''Franchise/{{Terminator}}'' series, the titular machines have detailed files on human anatomy to make them quick, effective, and efficient killers in almost any scenario. When reprogrammed to protect someone, however, these same files make the machine a fantastic field medic: the ''polar opposite'' of what these things are meant to do.

* P.J. O'Rourke's ''The Bachelor Home Companion'' has a lengthy list of alternative uses for household utensils. (For instance, did you know that an upended steam iron can be used as a hotplate? Also, while a regular screwdriver makes a good tool for spreading putty, a Philips head screwdriver would be useless for that purpose: it should be used to punch holes in cans of beer when the pop top has broken off.)
* In ''LightNovel/SwordArtOnline'':
** Kirito has a unique skill <> from the game [[TitleDrop Sword Art Online]]. When he got out of the game and started playing another game called Alfheim Online, he lost the skill but managed to use it by chaining one-handed abilities with each of his hand, controlling both of his hands separately by using muscle memory and calculating his skill use timing with the skill cooldowns. It was not supposed to happen at all, [[HandWave but he does have the excuse of having the best reflexes in]] ''LightNovel/SwordArtOnline'' [[HandWave (which is why he got the aforementioned unique ability) and had to learn how to fight efficiently due to being a solo player]]. He used the blade his character got during its creation in Gun Gale Online (another thing that was not supposed to happen) to deflect bullets shot by other characters with help of their own targeting markers. After returning to Alfheim Online, he started using his blades to deflect spells as well.
** One character in ''Sword Art Online: Lost Song'' is nominally a Leprechaun character who can somehow also dual wield. It turns out that this ability is due to their races' natural ability to utilize any races' weapons temporarily for the purpose of crafting/strengthening them - and the ability is actually ''multi-wield'' - as in their OSS, Thousand Swords.
* In the ''Franchise/{{Star Trek|NovelVerse}}'' novel ''The Kobayashi Maru'', this is possibly the real point of "the ultimate test of character"; Everyone who has "beaten" the Kobayashi has been a Grade-A badass. The method they use pretty much defined their career. Kirk conned the system like the improvising madman he is, but most of his named crew have taken it as well.
** Sulu went the diplomatic route and left the Kobayashi Maru to its fate, justifying it as a trap. The first to ever do it.
*** Mackenzie Calhoun of the ''Literature/StarTrekNewFrontier'' books actually one ups Sulu by [[ShootTheHostage destroying the Kobiashi Maru]] and warping out immediately.
** Chekov kept taking out enemy ships until his weapons were gone, then he kamikazed. Took out dozens before that point.
** But perhaps the best of all was Scotty, who just kept coming up with new engineering tricks[[note]]the Perera Field Theory, if you're curious[[/note]] which mathematically should work, but doesn't in practice (kind of like the theory of igniting the Earth's atmosphere with a nuke - as Scotty knows full well since he was the one who tested it) and the system just kept escalating until the computer actually spawned more ships than actually existed in known space at that time, all warships equipped with offensive and defensive technology that hadn't even reached the prototype stage yet. And it still didn't even slow him down. At that point the examiners shut the damned thing down themselves, perhaps in fear that the simulator was about to go Terminator on them.\\
At the time, he didn't know about the "unwinnable" part of the situation, and when he was debriefed he showed off a dozen or so more tricks he'd come up with while he was waiting. The examiners looked at everything he'd come up with and determined that the only way that the simulation could potentially beat Scotty would be if he spent several days of outwitting it before collapsing out of sheer exhaustion. Scotty then protested that if he had access to an actual engineering room, he could have beaten the simulation. The admiral in charge of the test, ''not'' amused by this cheeky solution, boots Scotty out of the command stream... and into pure engineering, which they both know is [[{{Unishment}} what he really wants anyway]].\\
...Aaand there you have Montgomery Scott's career in Starfleet. Turns out they knew it all in advance.\\
...Which makes Johnathan Archer pretty much the biggest JerkAss ''ever'' in the reboot, throwing away Neo over losing his damn dog...
* ''Literature/StarCarrier'':
** Terran Confederation {{Space Fighter}}s are equipped with AMSO canisters, missiles packed full of granules of degenerate matter ("sand") that are used as anti-missile countermeasures. At the end of the first book a squadron led by Lieutenant Trevor Gray accelerates to near lightspeed before releasing them and rather thoroughly [[PrecisionFStrike fucks up]] an incoming Turusch battlefleet. Gray acquires the callsign "Sandy" for this and is later described as having added a footnote to the manual. By book four, twenty years later, this has actually become a standard maneuver.
** Also in book four, Gray's SuspiciouslySimilarSubstitute Lt. Donald Gregory brings his fighter in an extreme close-range pass against a Slan warship (the narrator the sound of his fighter ''scraping the hull''), allowing him to [[WeaponizedExhaust insert his drive singularity inside the ship]]. This destroys it from the inside out.
* Creative use of technology is a hallmark of craftier characters in the ''TabletopGame/BattleTech'' universe. For example, there's Kai Allard-Liao, who was forced into an unfair six-versus-one training fight due to the machinations of his cousin. The training exercise disables military communications, including contact with GPS satellites--as a result, he has no overhead map and no idea of where his foes are. However, the exercise programming didn't disable contact to civilian equipment... so he finds the frequencies for ''geographic survey satellites'', which he promptly commands to look down at his area and report sources of low-level seismic activity. Turns out that HumongousMecha footsteps register on the Richter scale, granting him instant improvised tracking of his opponents. Even his more honorbound trainers declare the move 'incredibly resourceful,' much to the fury of his notoriously unhinged aunt.
* ''Literature/HarryPotterAndTheHalfBloodPrince'': Fred and George invent a hat with a built-in Shield Charm that lets the wearer NoSell most spells, the idea being to wear it and laugh at your friend's attempts to jinx you. Instead, it becomes one of their best-selling items as the Ministry, desperate for any kind of protection (having received a brutal awakening as to the return of Voldemort), has ordered half a thousand for its staff (it turns out very few people can do a Shield Charm by themselves).
* ''Literature/ArtemisFowl'' has a mining laser quickly converted into a very illegal weapon by many street gangs.

[[folder:Live Action TV]]
* The ''entire'' premise behind ''Series/MacGyver''. Not only does he put together some creative devices with the tools at hand in ways most would not expect, he often doesn't even use the tools at hand in the logical fashion--in one instance, he is locked in a room and has a revolver, but as he he DoesNotLikeGuns, he disassembles the bullets, puts the gunpowder into a hanky, sticks a primer in one side, puts the whole thing into a keyhole, and gives the primer a good hard rap with the butt of the gun, blowing out the deadbolt. It honestly would be so much easier to ShootOutTheLock, but the man has his standards.
* ''Series/MythBusters'' does this to the point that during the "airplane on a conveyor belt" myth Jamie pauses for a moment when he realizes that for once they ''are'' using a commercial product (specifically a remote-control model airplane) in the way it was intended to be used.
* In ''Series/{{Dinosaurs}}'', Baby likes hitting Earl over the head with a frying pan, until one breaks, and the Sinclairs try to use the frying pan's warranty to get a new one. The manufacturer denies the claim as the frying pan was meant for cooking, but the warranty didn't specify "cooking", it said the pan was guaranteed for "normal use", and in the Sinclair house, the "normal use" of a frying pan is Baby hitting Earl over the head with it.

* Scratching records in hip-hop. In a similar vein, overdriving a guitar amp to distort the sound.
* The Roland TB-303 was supposed to just play a preprogrammed repeating bass line. Then someone noticed what happened when you tweaked the filter knobs while it's playing, and the genre of Acid House was born.
* AutoTune was originally intended to change the frequency of the singer's singing or musician's playing to the correct one. Then Mark Taylor and Brian Rawling noticed while working on Cher's "Believe" that if you set it on the most aggressive setting, it sounds unnatural, but kind of neat.
** On a deeper level, the technology behind Auto-Tune wasn't originally developed for music production at all - it was to help oil drillers interpret seismograph data.
* Circuit bending: the act of taking a device that makes sound (for example, a children's toy), modifying the hell out of it, and then using said device to make music.

* Time outs in several sports:
** For instance, Basketball and Lacrosse. Intended to allow teams to meet and plan strategy. Can be used tactically to prevent a player from losing possession and restart play in a controlled manner. Only possible in "American" basketball. Other countries (under FIBA rules) will only allow a time out when the time is already stopped.
** UsefulNotes/AmericanFootball:
*** The most common use for a timeout is to stop the clock, and the second most common is to avoid a penalty for delay of game or too many men. It's far rarer for a timeout to be called to talk strategy on a critical play.
*** Somewhat less common is the use of a timeout to "ice the kicker". If your opponent is about to kick a field goal, some coaches believe that calling a time out ''just before'' the play starts will mess with the kicker's psyche enough to cause him to miss the field goal when he does eventually kick it. This is only done occasionally, however, because in most circumstances time outs are much more valuable for the above-mentioned unintended uses than for this one (if it ''is'' done, it's generally done at the end of a half, since the team in question probably won't get another chance to use it). Icing the kicker at the pro level generally does not work unless it is an incredibly long distance, and if mistimed, often just serves to give a free warm-up kick to the kicker; since there is usually no penalty on the kicker for kicking even if the whistle is blown, the kicker is often instructed to just follow through on the kick even if the play is blown dead.
*** An interesting use for a timeout was discovered on 12/8/13 in the game between the Philadelphia Eagles and the Detroit Lions. The Lions called timeout before an extra point attempt in order to clear snow out of the kicker's way. The kick got blocked anyway.
*** [[TakeYourTime Delay of game infractions]] in American football are charged on the offense when they allow the play clock to run out without snapping the ball as a way to prevent a team in the lead to just sit on the ball for huge chunks of time. The penalty is five yards. There are some occasions, though, when a team will intentionally get flagged for delay of game because [[{{Unishment}} they want to back up five yards to give their punter more space]] to punt the ball deep in the "coffin corner" (as close to the opponent's goal line as possible without crossing it - a punted ball that touches the end zone is called as a touchback and the opponent will get the ball at their own 20-yard-line). It's less common now, as opponents have taken to declining the distance penalty.
** Similary to icing the kicker in American football, a timeout will often throw off the server in volleyball. The practice is so widespread that in many matches, that's almost all it's used for.
** Modern flat track Roller Derby, depending on whether or not the Head Referee lets you get away with it. Calling a time out when there is less than 30 seconds left on the period clock can allow you to sneak in one last final jam when the time out ends, which must then be played to its natural conclusion (up to two minutes) even if the period clock runs out.
* Olympic fencing's flicks and whip-overs. Fencing weapons are nowhere near as stiff as swords for obvious reasons, so fencers have used these properties to deliver non-standard attacks that count in the rules of electric fencing but would make no sense if the weapons were real swords. Generally fencing can be viewed from both a traditionalist and competitive point of view, so the same fencer who flicks in a tournament might not in a casual bout. The sport's governing body, the FIE, has put a serious {{Nerf}} on flicks, but they remain viable.
* The cages used in MixedMartialArts were merely meant to be a structure keeping the combatants in one area (rings have been used and still are, but due to the grappling nature of the sport, these are becoming less and less popular due to people falling out of them.). Fighters soon learned they could be used to stand up from the ground, holding your opponent against it do damage, etc. This is viewed as both good and bad, depending, but has become such an integral part of the sport many fighters train specifically for using the cage effectively from different positions.
** Blatantly grabbing the fence is illegal however. This was established as a rule fairly early, as people were doing this to stop takedowns and get up from the ground more easily. Originally, the rules said nothing about grabbing with your toes however, and many fighters exploited this. The Unified Rules of MMA recently outlawed this practice.
** The short-lived YAMMA organization experimented with a bowl type cage, which in theory would keep action moving better. What ended up happening in the one event they did was wrestlers found it great for backing people against the raised edges and taking them down more easily for some lay and pray.
* In both the NFL and college, there is a system where a player can be kept for an extra year without counting against your roster (the IR system in the former, a medical redshirt in the latter). Many teams will play up an injury which is serious enough to keep a promising but raw player out most of the year in order to use these to gain an extra year of training. Both leagues have begun to push back against this practice, however.

* Benzoyl peroxide is commonly marketed and used as a treatment for acne, but for toy collectors (particularly doll collectors), such peroxide creams, most especially the 10% Oxy variety, are recommended for removing ink and dye stains on Franchise/{{Barbie}}s and Franchise/AmericanGirl dolls.
* SC Johnson's Future brand of acrylic floor polish (now marketed in the States as [[http://www.pledge.com/en-us/products/pages/floor-care-finish.aspx Pledge FloorCare Finish]]) also found a similarly unrelated niche amongst scale model hobbyists, to which the latter use the substance for coating windows and canopies for model aircraft and other vehicles.
* For some reason, hobbyists have taken an interest in installing Linux or Android onto educational children's toys, particularly tablets or game consoles targeted at younger audiences. As long as it has a color LCD screen on it or connects to the TV, hobbyists want to see if it can run Linux or Android. If it already runs Android, hobbyists want to get rid of the ''kiddified'' UI and put in a more adult-oriented one.
* Then there's the music scene. If toys are not outright circuit-bent, the sounds are sampled and used as part of the artist's music for one reason or another.
* The ''Nimbus 2000'', a piece of tie-in merchandise from the Literature/HarryPotter films. It's meant for kids to sit on and run around pretending to be little witches and wizards, with the vibration function meant to add realism. Teens and adult women found some, erm, more pleasurable use for the toy.

[[folder:Tabletop Games]]
* [[https://en.wikipedia.org/wiki/Dominoes Dominoes]]. They're meant for playing, yet people are more fascinated when they stack the tiles and let one tile topple the other.
* ''TabletopGame/{{Exalted}}'': the Twilight Caste were originally conceived as TheSmartGuy of the group, with their caste abilities inclining them toward sorcery, teaching, dealing with spirits and demons, solving crimes and building stuff. Due to their brokenly strong anima power, they became the preferred ''melee fighters'' of the Solar Exalted until they were hit by several consecutive rounds of errata aimed at putting the [[DoAnythingSoldier Dawn Caste]] back at the peak of warrior skill where they were originally supposed to be.
* ''TabletopGame/DungeonsAndDragons'' and (to a lesser extent) ''TabletopGame/{{Pathfinder}}'' players are notorious for exploiting these. Whole message boards are devoted to optimizing builds by using abilities in strange ways. Among the more egregious abuses include turning a spell called Locate City into a massive lethal explosion (brings new meaning to "[[DungeonBypass Scry and Die]]"), doing infinite damage with a dagger much too small for a human to consider more than a toothpick, and turning cannon fodder monsters into lethal encounters for powerful players with devious traps. Of course, the counter is always an attentive DM who puts his/her foot down and says "RuleZero, you can't do that."
** Another, the "Peasant Railgun", involves an extremely sketchy comprehension of physics. The idea being that the last man in a line gives a spear to the man in front of him, a series of actions that takes 6 seconds according to game mechanics. Thus the spear ends up moving with a speed that increases the longer the line is (with speed equal to distance traveled divided by a time period of six seconds), and thus should be moving at supersonic speeds when it reaches the front of the line.
** One thread was dedicated to necromancers using zombies to respond via yes/no actions... essentially, creating a giant computer.
** During a previous incarnation of Wizards of the Coast's forums, there were ''two'' optimization forums. One (Character Optimization) was dedicated to optimizing character builds. The other (Theoretical Optimization) was dedicated to outright insane but legal per the rules as written builds (in other words, CO was the board making things most [=DMs=] would let past, TO was the board making things no sane [=DM=] would ''ever'' let be used).
** Summon magic is, quite obviously, meant to summon a creature to fight on your behalf. In version 3.0, though, spellcasters tend to find it more useful to summon a whale [[GravityIsAHarshMistress directly above the enemy's head]]. [[ObviousRulePatch 3.5 changed the rules so that you can only summon creatures into an environment capable of supporting them]].
** The 3.5 [[PsychicPowers psionic power]] ''control body'' lets the user move another creature telekinetically like a puppet and force them to attack things. While intended as a way to disable enemies, some characters instead used it on themselves in order to make up for poor physical strength. What's more, since targets of ''control body'' aren't prevented from using PsychicPowers, it could be combined with ''solicit psicrystal'' (transfers control of one of your ongoing powers to your [[{{Familiar}} psicrystal]]) to effectively get double turns. ''Psionics Unleashed'', a ''TabletopGame/{{Pathfinder}}'' port of the 3.5 psionics rules by Creator/DreamscarredPress, adds a rule that [[ObviousRulePatch you can't use Control Body on yourself]].
* In TabletopGame/SpheresOfPower, the Skilled Casting drawback ties your magic to a Perform, Profession, or Craft check. This is so you can do flavorful things, like MagicMusic (via perform), or being able to [[WeatherManipulation control the weather]] because of how skilled a sailor you are (via Profession), or [[GeometricMagic making runes to hold your magic]](via Craft). However, ANY Perform, Profession or Craft check can be used, so you can declare your ability to summon lightning be tied to how well you can make cupcakes.
* In ''Tabletopgame/BattleTech'', [[HumongousMecha battlemechs]] can carry friendly [[PoweredArmor battlearmor]] into combat, at the cost of being unable to fire their torso-mounted weapons along with making the battlearmor easy targets. When the mechanic was first introduced, players quickly realized that you could just [[HumanShield pile battlearmor onto your mech and use them as free armor]], because the battlearmor would take hits that would otherwise damage the mech's torso. Later fixed in an ObviousRulePatch.
* ''TabletopGame/Warhammer40000'':
** InUniverse: The massive suits of Tactical Dreadnought (aka, Terminator) Armor, which can resist a few shots from anti-tank weapons were at first used to protect people working on plasma reactors while the reactor was on.
** Thanks to some poorly-thought-out mathematics, one player discovered that igniting the equivalent of a supertanker-ful of promethium (in other words, far less than the mighty refineries of the Imperium can contain) would result in a fireball that dwarfs the Sun. Cue the idea of using freighter ships loaded with the stuff on kamikaze runs.
* According to the rules in a ''TabletopGame/WarhammerFantasyRoleplay'', one of the low-level spells was intended to make emergency, temporary torches: the object the spell was cast on would glow brightly for an hour before vanishing. Players figured a waiting period of an hour was a fair trade for ''permanently disappearing a boss''.
* The majority the titular ''TabletopGame/{{Numenera}}'' have been unburied so long AfterTheEnd that nobody knows what they used to do at all and no instructions have survived. As a result, while the rulebook's equipment section speculates what the devices may have done, a long time ago, it is firmly said that the characters only care about what they can do for them ''now'' (such as, for example, a shield made for blast furnaces used in combat).

[[folder:Western Animation]]
* In ''WesternAnimation/MiraculousLadybug'', the butterfly Miraculous was made to [[SuperEmpowering temporarily empower ordinary civilians]] to aid against villains a la ''VideoGame/TheWonderful101''. BigBad Hawk Moth uses it to inflict DemonicPossession on his victims and turn them into supervillains to wreak havoc in Paris.

[[folder:Real Life]]
* Under Australian consumer law, you are entitled to a refund or replacement if an item you purchased is not fit for its intended purpose. This obviously means the task it was originally designed for, but also, if you conveyed a different purpose to the person you bought it from, and it's not suitable for ''that'' purpose, you are still entitled to a refund/replacement.
* There are entire websites dedicated to "lifehacks", which are basically creative ways to use everyday things.
* Cars have long come with a built-in cigarette lighter, intended to [[CaptainObvious light cigarettes.]] The 12-volt socket the lighter plugs into was designed specifically for it -- but inventors soon realized it could be used to power other convenient gadgets. Now, between the success of these gadgets and the decline of smoking, many cars come with several 12-volt sockets and no lighter at all!
* Patent laws were meant to protect the creators and inventors from having their creative endeavors exploited and stolen, ensuring they would be compensated. Due to loopholes in the law, they do nothing to stop businesses from buying up patents and suing others for using it (at least in the U.S.), often under vague interpretations of use. Given that fighting lawsuits is more expensive than settling, entire companies have been set up to do just this (often called Patent Trolls).
* Military rules and regulations are prone to this, due to the military culture of following orders to the letter, often ignoring the spirit of it. These can be exploited by the common troop to get away with things, or by commanding officers looking to punish someone.
* Quite a few popular drugs started life as treatment for something else, but the side-effect was so interesting that it soon became almost exclusively known for the non-intended use:
** Heroin, for example, was originally used to treat Morphine addiction. What happened right after that is obvious.
** Of all drugs, Viagra and Cialis began this way. Created to treat pulmonary hypertension and angina pectoris, it turned out that the tissue responsible for erections responded in the same way as the original target for the drugs, so both drugs were rebranded and distributed as a drug for erectile dysfunction before being tested and approved for the intended use.
** Rogaine (a topical treatment for baldness) was also originally developed to treat hypertension.
** Most over-the-counter sleep aids use the active ingredient diphenhydramine, which is better known as Benadryl, an antihistamine that has drowsiness as a side-effect. So the companies just started marketing the side effect as a primary effect.
** Cough syrup works not by soothing your throat, but by shutting down the cough reflex in your brain. Taking it in excessive doses is psychoactive on par with illegal street drugs, but it's not illegal because there's no other known way to treat coughs, and it's downright nasty (the taste being enough to make people vomit from that alone).
** As famously described in ''TheWolfOfWallStreet'', Qualuudes began their life as a sleep aid. However, users noticed that after taking them if they resisted the urge to sleep, it would have a very powerful psychoactive effect. The popularity of the secondary use eventually led to them being banned.
* AK-47 magazines make excellent bottle openers. So do the iron sights of several missile launchers. People have used them so much (damaging the magazine) that weapons such as the IMI Galil rifle included actual bottle openers as part of their furniture to prevent loss of combat efficiency.
* Many products were originally sold for an entirely different purpose, only for consumers to find a ''much'' better use. One famous example are Kleenex Tissues: They were originally marketed as make-up removers until the company noticed the majority of people buying them were women ''and'' men using them to blow their noses instead.
** Similarly, cotton swabs (AKA Q-tips) are theoretically intended for applying makeup or antiseptics. Everyone and their mother uses them to clean their ears out, even though the package says you're not supposed to.
* USB ports, which were originally intended to allow peripherals to interface with computers, have the added feature of a 4.5V power line. There are AC adapters that completely ignore the data lines to provide power for charging or running portable devices, and they are fast becoming the standard for things like cars, and airplane and bus seats, where a low-voltage DC power supply is desired. You can now even buy receptacles with built-in USB ports specifically for charging your devices without an adapter right at home.
* Graphics cards are designed to perform certain types of operations on lots of data very quickly. This means that if you have a problem that can be reduced to one of those operations and a lot of data to do it on, you can co-opt the graphics processor to do it. It turns out that certain kinds of physics computations fall into this category, so early "graphics workstations" were extremely popular with physics and chemistry departments for reasons the designers never expected. More recently, high-performance graphics cards have been used to allow much faster Bitcoin mining than is possible otherwise.
** Outside of PC graphics cards, video game consoles such as the XBox contained powerful processors and were being sold at a loss to recoup the pricing in games. Predictably, people wanting raw processing power bought up the consoles to make use of that hardware for calculations.
* In the early days of skiing (and still sometimes on more rural areas), old cars had their drive wheels hooked up to rope pulleys. With another pulley mounted on the top of a slope, the wheels lifted from the ground, and the car in forward idle, a makeshift rope tow ski lift would be created.
* Changing your web browser's user agent string, which among a few other minor details tells a website which browser you're using for the purposes of compatibility, isn't something an everyday web user would ever have to worry about. That is, until people realized they could use the old-style of Website/{{Google}} (as well as other sites) which some people prefer by using a plugin to tell the site they're using a browser incompatible with the new style of Website/{{Google}}.
* You ''could'' go to the office store and buy a paper weight. But most people would simply use whatever happens to be nearby such as a mug or anything else that's both heavy and small enough.
* As the name implies, the Fender Jazzmaster was a guitar designed with jazz music in mind. Ironically, it was largely ignored by jazz musicians and instead it quickly became a hit with SurfRock guitarists. The guitar was popularized once again by a number of AlternativeRock bands and artists from TheEighties onward.
* [[CaptainObvious Iron bombs are designed to hit ground targets]]--the only guidance they have is gravity, after all. However, a particularly creative USAF pilot found himself having to deal with enemy [=MiG=] fighters while in his relatively slow and somewhat ungainly F-105 fighter-bomber, and elected to fly higher than the enemy fighter and eject a rack of bombs he had been carrying. The [=MiG=] pilot hadn't expected that move for fairly obvious reasons, and may go down in history as one of a very few fighter craft to have been bombed in mid-flight.
* Microsoft Excel may have been designed as an accounting and spreadsheet program, but it can be used to classify and organize all kinds of things. As just one example, historians may use Excel to organize, classify and summarize research materials. Taking it UpToEleven, one Tumblr user's grandmother found a [[http://i.imgur.com/hZFvwVm.jpg completely different use for it.]].
** Microsoft Excel may just be the software king of this trope, it has been used for everything from letter-writing (instead of Microsoft Word? Why? Because the grids make it easier to align the text!) to filing taxes (screw Quicken!) to even being used as a ''[[https://www.cnet.com/news/play-an-rpg-made-in-excel/ game engine]]''!.
** Speaking of games, Microsoft Excel has Flash support. What is written in Flash? Games. Work in an office that has computers rigged to not allow .exe files and game sites blocked? Swing by [[http://www.exceltrick.com/interesting/excel-games-free-download/ here]] or make your own, save it as "Meetings.xlsx", and play at work. Take ''that'', Corporate America!
* Duct Tape. From making things from scratch to [[https://en.wikipedia.org/wiki/Duct_tape_occlusion_therapy curing warts]], you can quite literally use it for anything.
* Anti-materiel rifles are designed to be anti-materiel, i.e. effective at destroying military equipment. However, their high caliber and high precision also made them very effective at dispatching combatants from a very long range. Many of the longest recorded sniper kills are done with rifles that would have been considered anti-materiel rifles than general sniper rifles.