->'''Silk:''' You're an absolute gold mine of useless information, you know that?\\
'''Beldin:''' There's no such thing as useless information, Kheldar.
-->--''[[Literature/{{Belgariad}} The Malloreon]]'', '''Creator/DavidEddings'''

Some characters are vast stores of useless knowledge. Now, normally, you'd think that useless knowledge would never come in handy, right?

You'd be wrong.

Because, by LawOfConservationOfDetail, or maybe because of some usage of the IdiotBall, there will rise an ''exact'' situation where their trivial knowledge will come to the rescue. Sometimes it requires a PlotTailoredToTheParty to happen, other times it just happens naturally. In any case, their so-called "useless knowledge" will save the day. Of course, this is pretty much the mantra of the CrazyPrepared.

This is the subtrope of ChekhovsGun when the object is something a character ''knows'', though occasionally it is a DeusExMachina. May lead to ThisIsNoTimeForKnitting. Compare ThisLooksLikeAJobForAquaman, where it's a useless ''superpower'' that comes in handy. When it's a seemingly useless ''item or knick-knack'', ItMayHelpYouOnYourQuest.

ChekhovsHobby and ChekhovsClassroom leads to this. Compare FigureItOutYourself, YouWillKnowWhatToDo.
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!!Examples

[[foldercontrol]]

[[folder:Anime and Manga]]
* In ''AudioPlay/SaintBeast'', an angel helping Shin move drops a stack of his books and the first one Shin picks up is an old one he's had for a long time about witchcraft transformation. The MonsterOfTheWeek? An evil tree that's actually an angel who underwent witchcraft transformation.
* Back in volume 4 of ''LightNovel/HighSchoolDXD'', Sirzechs asks Ise as to what happens if the latter uses [[StatusBuff Gift]] on Rias' breasts, then tells him not to worry about it. Seven volumes later, [[spoiler:the spirits of the past Boosted Gear users bring it up again and sure enough, Ise uses said skill(with permission from Rias, who readily accepts), and the end result? Rias becomes a ''battery'' for Ise at the cost of her breasts ''shrinking'']].
[[/folder]]

[[folder:Comic Books]]
* A short ''Franchise/{{Batman}}: Black and White'' story by Creator/WarrenEllis and Creator/JimLee features Batman hunting down a murderous senator and fighting his way through his goons. Each skill that Batman uses is followed immediately by a one or two panel flashback showing how he learned it. These include [[CrazyPrepared building a remote control, knowing the smell of every aftershave ever, knowing the exact hole size and shape different caliber bullets make in different body parts, kicking a tree in half and identifying how recently someone had a manicure from the nail impressions left in skin.]]
[[/folder]]

[[folder:Films -- Live-Action]]
* This is pretty much the plot of ''Film/SlumdogMillionaire''. Although, it's less that the main character is full of useless information as it is every memorable event in his life happened to intercross with the questions. Sort of like if your life was a ChekhovsArmory.
* In ''Film/PlanetTerror'', Cherry Darling even calls many of her skills 'Useless talents' and numbers them.
* In ''Film/LegallyBlonde'', law student Elle Woods' extensive knowledge of fashion allows her to both a) discredit a witness and b) implicate the true guilty party in the case. And she does it again in the sequel, this time to prove that a certain politician was a) not getting a facial and b) secretly against a "no testing on animals" bill she's working on.
* ''Film/WaynesWorld''
** A security guard conveys suitably detailed explanation about the whereabouts of the big-time music producer Frank Sharp. Wayne hangs a lampshade on it at the time by commenting "For a security guard, he had an awful lot of information, don't you think?" Wayne lampshades this again later, when Sharp's whereabouts suddenly become important: "Aren't you glad we were there to hear that information? Seemed extraneous at the time."
** The sequel does something similar as well. When Wayne and Garth arrive outside of a studio, a number of men are doing things such as moving a window back and forth across the street, stacking fruit, and so on. When asked why, the workers reply that it's just their job. Later on Wayne crashes through them all in his car in a stereotypical "action sequence", causing the workers to state in satisfied fashion that their job is done. Of course, the "handiness" of this is almost entirely under the RuleofCool.
* ''Film/MontyPythonAndTheHolyGrail''. The argument in the beginning about where Arthur's henchman got the coconuts allows Arthur to pass across the bridge over the Bottomless Pit. Sadly, the musical ''Theatre/{{Spamalot}}'' used the argument at the beginning, but not the usefulness later.
* Subverted in ''Film/{{Titanic}}'' (1997): While being given a tour of the ship, Rose's entourage is shown the equipment in the Titanic's gymnasium, which includes a rowing machine. When offered to give it a try, Rose's mother remarks, "Don't be absurd. I can't imagine a skill I should likely need less!"
* It probably qualifies more as a ContinuityNod than anything else, but a cut scene in the 1979 sci-fi classic ''Film/{{Alien}}'' shows Warrant Officer Ellen Ripley reading a bioscanner for crewmember Kane, and failing to understand that he's had an organism planted inside of him. This scene pays off in the third film, when Ripley gets prison staff member Andrews to scan her using her crashed escape pod's bioscanner, and she knows where and how to scan for anomalies.
* ''Film/{{Mindhunters}}'' has one character know the exact speed of light, and this came in handy as to figure out how someone would be killed next.
* Inverted in ''Film/{{Paycheck}}'', where Ben Affleck's character is given the (temporary) foreknowledge of his own future, and based on this he gives himself an [[ItMayHelpYouOnYourQuest envelope full of odds and ends]] that he ''will'' need in the near future. However, he gets his memory wiped and must reverse engineer his own future to survive.
* Charles Morse from ''Film/TheEdge'' is a collector of useless trivia... some of which comes in very useful when he is stranded in the Arctic.
* Gloria from ''Film/WhiteMenCantJump'' collects useless trivia, which comes in handy when she gets onto ''Series/{{Jeopardy}}'' The categories are all her weird topics, like "Foods that start with the letter Q."
* In ''Film/DudeWheresMyCar'' one of the main characters regularly watches ''Creator/AnimalPlanet''. This eventually comes in handy as he learned that sometimes animals use tools like sticks [[spoiler:or straws]] and also something useful about [[spoiler:ostriches.]]
* In ''Film/MyCousinVinny'', a load of very specific information about old cars comes in handy at the end of the trial. So does Vinny's newly acquired knowledge of how to cook grits.
* ''Theatre/TheHistoryBoys'' plays with this a lot.
** A first example:
-->'''Timms:''' Most of the stuff poetry's about hasn't happened to us yet!\\
'''Hector:''' But it will, Timms, it will. And when it does you'll have the antidote ready.
** As well as the scene with the evangelical gym teacher.
-->'''Wilkes:''' One day it'll save your life.\\
'''Posner:''' Nothing saves anyone's life. It just postpones their death.\\
'''Wilkes:''' Jesus Christ will save your life, lad, if you'll only let him into your heart.\\
'''Posner:''' I'm Jewish, sir.
* In ''Film/TheRebound'', Sandy's knowledge of sports via fantasy competition is established early. It won't be long till that comes in handy.
[[/folder]]

[[folder:Literature]]
* Creator/DanBrown's ''Literature/AngelsAndDemons'' (as well as ''Literature/TheDaVinciCode'') is a particularly {{Anvilicious}} user of this trope. In a possible LampshadeHanging, ''A&D'' actually contains the line "He never suspected that later that night, in a country hundreds of miles away, that information would save his life," regarding the fact that one square yard of drag will slow a falling body almost 20%.
* The page quote comes from ''[[Literature/{{Belgariad}} The Malloreon]]'' by David and Leigh Eddings. Sure enough, towards the end of ''The Malloreon'' something Beldin said turns out to be of vital importance: both the heroes and villains need to find out where to go for the final showdown from the Seers at Kell, when [[spoiler:Belgarath remembers Beldin mentioning "the Grolims are still afraid to go near Kell" -- the villains can't go themselves.]] Of course, this is something that Beldin and Belgarath have both known perfectly well for centuries. It's common knowledge among the world's sorcerors and, of course, the Grolims. Mentioning it early in the story for later use is an excellent example of ChekhovsGun, but this may not exactly fit the trope since it isn't ''unusual'' knowledge. The page quote ''itself'' simply refers to Silk learning that green is made from blue and yellow... which had absolutely no impact on the plot beyond explaining [[spoiler:why the Sardion was red]].
* ''Literature/WatershipDown'' has a couple instances of this.
** Early in the book, the rabbits discover that sitting on a floating piece of wood allows a rabbit to float. This is a difficult concept for such simple animals, and only a couple of the group can wrap their heads around it. After using this principle to help a wounded rabbit get across the brook, Blackberry comments: "I admit it was a good idea. Let's remember it. [[LampshadeHanging It might come in handy]] [[{{Foreshadowing}} again sometime]]." And of course, [[spoiler:it ''does''. When the rabbits have to make a quick getaway from an enemy patrol, their plan hinges on getting on a little punt and biting the rope. The enemy rabbits (and many of the escapees) are completely baffled by this tactic.]]
** Hazel, on an impulse, saves a mouse from a kestrel. This is seen as unusual because rabbits usually have no associations with other non-predator species. Hazel, however, sees it as an opportunity. Mice are fairly useless to the rabbits, but what would be the benefit of befriending a more useful animal? Enter Kehaar. Not to mention that the mouse [[spoiler:warns them of the arrival of the Efrafa rabbits]] later on.
* Sazed in ''Franchise/{{Mistborn}}'' knows a lot about old religions. This may seem useless but [[spoiler:using it he is able to move the world back to its proper distance from the sun and put the continents in the right places.]]
* The god Shemhazi's motto in the ''Literature/KushielsLegacy'' series is "All knowledge is worth having." Phedre, Joscelin, and later Imriel quote it at times.
* Creator/LarryNiven [[LampshadeHanging lampshades this]] in his ''Literature/KnownSpace'' series. Two of his earlier ''Known Space'' stories, "Eye of the Octopus" and "How the Heroes Die" detail the early manned exploration of Mars, and include the characters collecting seemingly trivial data about the planet that isn't useful at the time. In the novel ''Protector'', set a hundred years later, the trivia about Mars is finally put to use. When asked how the Terrans knew such useless knowledge would one day be useful, Lucas Garner says, "No knowledge is really useless... you'll always find some use for it sooner or later."
* In ''Literature/ThePaleKing'', it is randomly revealed that [[spoiler:Director Glendenning has a pathological hatred of mosquitoes.]] It comes back in a big way in one of the last chapters.
* Literature/SherlockHolmes practically defines this trope, what with his knowledge of everything from cigar ash to medical school mnemonics to tattoo techniques.
* The book on which the aforementioned ''Slumdog Millionaire'' is based, the excellent ''Literature/QAndA'' by Vikas Swarup, unquestionably belongs in the literary examples of this trope.
* In ''Literature/{{Island}}'', Ian is a little kid who spent all his time watching the Discovery Channel and other informative TV channels. It ends up saving the group's life more than once when the group of preteens, ages 11 to 14, get marooned on an uncharted island by themselves [[spoiler:well, not really by themselves. There's also a terrorist group on there too]].
[[/folder]]

[[folder:Live-Action TV]]
* On ''Series/{{Cheers}}'', [[TheClavin Cliff]] somehow [[ShowWithinAShow ends up a contestant]] on ''Series/{{Jeopardy}}''. The clue categories align perfectly with his idiosyncratic "knowledge" (mothers, the Post Office, etc). He dominates the first rounds, amassing a pile of winnings, but of course ends up stupidly [[ResetButton blowing it all]] in Final Jeopardy.
* On ''Series/{{Bones}}'', one of the interns, Mr. Nigel-Murray, spouts off useless facts only vaguely related to the case whenever he gets nervous. Occasionally, his useless facts turn out to be helpful.
* In an episode of ''Series/TheGoodGuys'', Jack and Dan track down a criminal to a restaurant because of barbecue sauce left at the crime scene. When Jack asks Dan how he knows which specific restaurant the criminal ate at, Dan responds, "There's three things I know something about: fast cars, fighting crime, and the various good barbecue in the Dallas metroplex."
* ''Series/{{Glee}}'':
** In the episode "A Night of Neglect", the random substitute teacher trivia and later academic decathlon category is "hermaphrodite Nazi sympathizers".
** Brittany, who is anything but bright, helps the team win with her incredible knowledge of cat diseases.
* In ''Series/CriminalMinds'', Dr. Spencer Reid is the ''king'' of this trope. Knowledge of Siouxsie and the Banshees, 14th-century English literature, and government-issued traffic reports? You betcha.
* The "The $99,000 Answer" episode of ''Series/TheHoneymooners''. Music-guru Ralph learns he is to be a contestant on a music trivia game show and Norton helps him practice for the show by playing snippets of various songs on the piano. To Ralph's ever-increasing annoyance, Norton always warms up by playing the first two lines of "Old Folks at Home" ("Way down upon the Suwanee River, far far away"). When Ralph confidently appears on the game show, the first musical clue he hears is the same two lines that Norton always warmed up with. Ralph is dumbstruck, can't come up with the answer, and is eliminated from the game on the very first question. For the record, [[CrowningMomentOfFunny he guessed that Norton composed it]].
[[/folder]]

[[folder:Music]]
* This is Invoked by Creator/TomLehrer on the live album version of his performance of ''The Elements''[[note]]A song which lists the chemical elements (at least, those known at the time) "set to a possibly recognizable tune"[/note].
-->'''Tom Lehrer:''' This may prove useful to somebody some day, perhaps, in a somewhat bizarre set of circumstances...
[[/folder]]

[[folder:Tabletop Games]]
* ''TabletopGame/DungeonsAndDragons'':
** In ''D&D'', this is exemplified by the Bardic Knowledge ability, where a Bard might have some random information based on lore he's heard in his travels.
** All of the gnomes (an entire nation's worth) in the ''TabletopGame/{{Eberron}}'' setting collect information constantly, just in case some bit of it comes in handy later.
* In the ''TabletopGame/NewWorldOfDarkness'' TabletopRPG, EncyclopedicKnowledge, which is a four-dot Merit (keeping in mind that you only get seven dots for Merits at character creation), is basically this, allowing you to make a roll anytime you come across...well, ''anything'', really, that might cause you to remember something you once read/heard/saw that might be pertinent to the situation. Also, you can ''only'' buy it at character creation, because "you've either spent your life soaking up useless trivia or you haven't".
* In the ''TabletopGame/OldWorldOfDarkness'' setting, a similar effect could be achieved by taking the 5-point "Jack of All Trades" Merit, which basically gave you an "illusory" 1 dot in every Skill and Knowledge, counting as basic training/understanding of each of those abilities. To actually build any of them up required buying the first dot from scratch.
[[/folder]]

[[folder:Video Games]]
* Done in ''VideoGame/BanjoKazooie''. Throughout the castle, you'll come across Gruntilda's (good) sister Brentilda, who will happily tell you all of Gruntilda's embarrassing secrets. Later on, when Grunty challenges you to a quiz style board game, these secrets become your only means to win. Note that it's possible to avoid answering the "Gruntilda Questions" for the most part if you make a slight detour to get a Joker (which lets you skip a Question). In fact it's possible to finish the Board without having to answer ''any'' Gruntile Question. Also, the answers to each question is different, and change with each play through of the game. So getting Brentilda to give you the facts becomes necessary each time you play.
* ''VideoGame/{{Portal 2}}'': (paraphrased) "Moonrocks crushed into powder and then mixed with water"..."makes a great conductor for portals" becomes extremely useful during the final boss battle, not only at the beginning but [[spoiler:at the end your character shoots a portal into the moon, thereby sucking the BBEG into space]].
* In ''VideoGame/FinalFantasyII'', it turns out that your usually-silent friend and party member knows beaver language. Guess who becomes your interpreter when you run into giant beavers.
* Averted in ''VideoGame/FinalFantasyVII'' when you search a locker in the Shinra Building and find a megaphone. Cloud sees no reason why he would need it, so he just leaves it there. The next time you visit the building you have since acquired a party member who [[ImprobableWeaponUser can use megaphones as weapons]], so you can pick it up if you remember to search the locker again.
[[/folder]]

[[folder:Web Original]]
* ''Literature/WhateleyUniverse'':
** Phase is CrazyPrepared enough to pull this off. In the fourth Phase story, he obsesses to teammates about the New Olympians, who might just be incarnations of the real Greek Gods [[spoiler:(all of them are)]]. In the seventh Phase story, the team is trapped in a holographic simulation facing simulacra of... the New Olympians. Phase pulls out his knowledge of them to figure out how to beat Counterpoint and how to rescue Lancer.
** Phase learning about "giants" (size Warpers who use a warp field to appear to grow to giant size) in class, and then using that to defeat one in Boston. He also uses the same tactic to defeat the Vindicators in the beginning of ''Ayla and the Birthday Brawl'' -- he takes over Sizemax's field and uses her like a meteor hammer.
** Phase is made of this trope, when he's not being CrazyPrepared or a ShelteredAristocrat. There's the lecture he gave on fighting other mutants in "Ayla and the Birthday Brawl". There's the training manual he read in "Ayla and the Great Shoulder Angel Conspiracy". There's the financial expertise he learned about as a child in a super-rich family. There's the knowledge about religious icons he wields in "Ayla and the Grinch". And so on...
* The Hermit, one of the TAROT villains from the ''Roleplay/GlobalGuardiansPBEMUniverse'' retains a perfect memory of everything he ever experienced from the time of his childbirth, and is a voracious reader. He's also one of the world's smartest people, allowing him to put his EncyclopedicKnowledge of ''everything'' [[CrazyPrepared to use against his opponents]]. He's a villain the heroes hate going up against, simply because he's so annoyingly effective.
[[/folder]]

[[folder:Western Animation]]
* Happens twice on ''WesternAnimation/{{Futurama}}''. In one case, Fry's knowledge of 20th-century TV is what saves the Earth from a horde of [[SeriousBusiness invading aliens]] (they wanted to see the final episode of a [[AliensStealCable TV show]] that was knocked off the air because Fry spilled beer on the TV station's control panel while delivering a pizza in the 20th century); and in the other case, Fry's knowledge of "good old-fashioned 20th-century garbage-making skills" saves the Earth from...a gigantic ball of 20th-century garbage...for now.
* Subverted in ''WesternAnimation/MegasXLR''.
-->'''Magnanimous:''' Now, lose the fight or I'll drop your friends into the ''quantum singularity''!\\
''[flashback to Coop not paying attention at school]''\\
'''Teacher:''' Mr. Cooplowski! Pay attention! One day you're going to need to know what a quantum singularity is, and then you'll be sorry!\\
'''Young Coop:''' Yeah, right.\\
''[back to the present]''\\
'''Coop:''' Uh, that's bad, right?
* In ''WesternAnimation/PinkyAndTheBrain'', Brain is on a game show, and Pinky annoys him by chatting in his ear. Pinky is about to talk about ''Series/TheHoneymooners'' when Brain silences him. The final question, [[GoldenSnitch worth everything]], is about--''The Honeymooners''. This is probably a ShoutOut to an episode of ''Series/TheHoneymooners'' where something similar happens.
* ''WesternAnimation/DaveTheBarbarian''
** This trope title comes from the episode "Termites of Endearment". Dave refuses to practice sword fighting because he's busy making decorative knick-knacks for sale, although nobody wants to buy them. His sister Fang badgers him to practice fighting, and Dave says "trust me, someday my love of decorative knick-knacks will come in handy!" He keeps saying this throughout the episode, usually directly to the audience. Then the MonsterOfTheWeek attacks, defeats everyone easily, and is about to kill them all--when it notices one of Dave's things and says, "did I ever tell you how much I love decorative knick-knacks?" Cut to Dave selling thousands of knick-knacks to the monster. Fang looks at him and says, deadpan, "I so hate you right now."
** And in another episode, it was his origami skills.
** And his Amazing Penmanship.
** And then his pastry baking skills.
** And Fang's bug-squishing abilities. (Notice a trend?)
* ''WesternAnimation/TeenTitans''. Beast Boy's bottomless well of TV trivia knowledge ultimately allows the Titans to defeat Control Freak, who was only dangerous because he also possessed a bottomless well of TV trivia knowledge.
* Subverted in ''WesternAnimation/RockyAndBullwinkle'': in the episode "Banana Formula", Bullwinkle eats a banana on which a secret formula for a powerful explosive was written (don't ask), but thanks to his ability to remember everything he ever ate, he remembers the formula, which is a big help for the bad guys.
* The ''WesternAnimation/KimPossible'' episode "Dimension Twist": Ron's family has just got cable TV and Ron has been glued to it for so long he's memorized the channels. Not something you'd need, right? Wrong. TrappedInTVLand with the hole that dropped him there threatening to undo all of reality, he knew what to switch to plug up the tear in the space/time continuum with a horde of monkeys.
* In one of ''WesternAnimation/DarkwingDuck'''s [[MultipleChoicePast origin stories]], the phrase "It could come in handy someday," is uttered by:
** His father, as he gives Darkwing his Omniblaster gas gun (just before his space pod takes off [[Franchise/{{Superman}} from their exploding home planet]]).
** His [[IKnowKarate Quack Fu]] master, upon completing his training.
** The genie he meets while travelling though the desert, who gives him his costume and his signature smoke-intro.
* There's a ''ComicStrip/{{Peanuts}}'' animated cartoon in which Charlie Brown becomes a spelling bee whiz due to only getting words like "failure".
[[/folder]]

[[folder:Real Life]]
* ''Series/WhoWantsToBeAMillionaire'': Since there was no hard time limit until recently, the contestant was always sure to regale the viewers at home with their life story every time they encountered a [[WarmupBoss $200 question]] that somehow related to it. The first contestant to win the full million (with no lifelines!) was asked which of the options was not a federal holiday. He informed the audience that he was a federal employee and [=BSed=] about it for a while before answering the question.
* ''[[http://en.wikipedia.org/wiki/Academic_Bowl Quizbowl]]''. Being a repository of completely random knowledge is an immense asset. Subverted by the [[http://www.qbwiki.com/wiki/Canon Canon]], thanks to which, experienced players can predict fairly accurately what topics will come up and study accordingly. Probably most of the points good players accumulate are the result of targeted accumulation.
* ''Series/{{QI}}''.
* ''Series/{{Jeopardy}}'', and trivia shows in general. Just look at Ken Jennings, the man with the longest-ever run on ''Jeopardy''.
* Pub Quizzes often have sections which are basically set up to encourage this.
[[/folder]]
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