Beldin: There's no such thing as useless information, Kheldar.
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 Law of Conservation of Detail, or maybe because of some usage of the Idiot Ball, there will rise an exact situation where their trivial knowledge will come to the rescue. Sometimes it requires a Plot Tailored to the Party 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 Crazy-Prepared.
This is the subtrope of Chekhov's Gun when the object is something a character knows, though occasionally it is a Deus ex Machina. May lead to This Is No Time for Knitting. Compare This Looks Like a Job for Aquaman, where it's a useless superpower that comes in handy. When it's a seemingly useless item or knick-knack, It May Help You on Your Quest.
- In Saint Beast, 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 Monster of the Week? An evil tree that's actually an angel who underwent witchcraft transformation.
- Ian from Fairy Cube has read every book that has any information on fairies since childhood. When Kaito transports him to the Otherworld and Ian has to proceed to get back out, he uses his knowledge to fight, using a pair of iron scissors that are an effective weapon against fairies and gets Ainsel across a sweetwater river so that the Nuckelavee chasing them can't follow them.
- Back in volume 4 of High School Dx D, Sirzechs asks Issei as to what happens if the latter uses Gift on Rias' breasts, then tells him not to worry about it. Seven volumes later, the spirits of the past Boosted Gear users bring it up again and sure enough, Issei uses said skill(with permission from Rias, who readily accepts), and the end result? Rias becomes a battery for Issei at the cost of her breasts shrinking.
- A short Batman: Black and White story by Warren Ellis and Jim Lee 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 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.
- In The Keys Stand Alone: The Soft World, Nangre the librarian advises George and Paul to collect the sayings, poem lines, and other bits of graffiti and trivia found just about everywhere. She says that these strange things are the feeble attempts of the gods to communicate with the outworlders, and have meanings that might not become evident for a long time. George dubs them "Gods Chat" and keeps a list.
- This is pretty much the plot of Slumdog Millionaire. 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 Chekhov's Armory.
- In Planet Terror, Cherry Darling even calls many of her skills 'Useless talents' and numbers them.
- In Legally Blonde, 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.
- Wayne's World
- A security guard conveys a 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 a satisfied fashion that their job is done. Of course, the "handiness" of this is almost entirely under the Rule of Cool.
- Monty Python and the Holy Grail. 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 Spamalot used the argument at the beginning, but not the usefulness later.
- Subverted in 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 Continuity Nod than anything else, but a cut scene in the 1979 sci-fi classic 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.
- 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 Paycheck, where Ben Affleck's character is given the (temporary) foreknowledge of his own future, and based on this he gives himself an 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 The Edge is a collector of useless trivia... some of which comes in very useful when he is stranded in the Arctic.
- Gloria from White Men Can't Jump collects useless trivia, which comes in handy when she gets onto Jeopardy! The categories are all her weird topics, like "Foods that start with the letter Q."
- In Dude, Where's My Car? one of the main characters regularly watches Animal Planet. This eventually comes in handy as he learned that sometimes animals use tools like sticks or straws and also something useful about ostriches.
- In My Cousin Vinny, 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.
- The History Boys plays with this a lot.
Timms: Most of the stuff poetry's about hasn't happened to us yet!
- A first example:
Hector: But it will, Timms, it will. And when it does you'll have the antidote ready.
Wilkes: One day it'll save your life.
- As well as the scene with the evangelical gym teacher.
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 The Rebound, Sandy's knowledge of sports via fantasy competition is established early. It won't be long till that comes in handy.
- Dan Brown's Angels & Demons (as well as The Da Vinci Code) is a particularly Anvilicious user of this trope. In a possible Lampshade Hanging, 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 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 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 Chekhov's Gun, 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 why the Sardion was red.
- Watership Down 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. It might come in handy again sometime." And of course, 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 warns them of the arrival of the Efrafa rabbits later on.
- Sazed in Mistborn knows a lot about old religions. This may seem useless but 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 Kushiel's Legacy series is "All knowledge is worth having." Phedre, Joscelin, and later Imriel quote it at times.
- Larry Niven lampshades this in his Known Space 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 The Pale King, it is randomly revealed that Director Glendenning has a pathological hatred of mosquitoes. It comes back in a big way in one of the last chapters.
- Sherlock Holmes 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 Q & A by Vikas Swarup, unquestionably belongs in the literary examples of this trope.
- Island (2000): 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 well, not really by themselves. There's also a terrorist group on there too.
- On Cheers, Cliff somehow ends up a contestant on 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 blowing it all in Final Jeopardy.
- On 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 The Good Guys, 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."
- 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 Criminal Minds, 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 Honeymooners, episode "The $99,000 Answer". 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, he guessed that Norton composed it.
- In the Leverage episode "The Corkscrew Job", we learn that while a winery now uses sophisticated technology to filter out deadly carbon dioxide from the lower levels of the winery, before that technology was available, they periodically opened certain doors in the upper level to allow the gas to escape. At the end of the episode, the owner of the winery shuts off said sophisticated technology in an attempt to kill someone via carbon dioxide poisoning and make it look like an accident, and Parker and Elliot use that knowledge to open those doors and release the gas.
- A rather awesome example occurs in the fourth season of Resurrection: Ertuğrul. Here, Ertugrul tells his son Gunduz a story about a cyclops-like creature named Tepegoz. One day, a brave man dealt with the beast by injuring it in the eye and although it didnt kill Tepegoz outright, it caused him to lose his eyesight and weakened him in the process. This story becomes useful when Gunduz is abducted by the mercenary Titan and taken to Karacahisar, where he encounters Tekfur Ares. After Ares announces that he wants to rechristen Gunduz to Kronos, the Beys son boldly pulls out a stone from his pocket and jabs it into one of Ares eyes, causing him to be half-blinded for the remainder of the season.
- This is Invoked by Tom Lehrer on the live album An Evening Wasted with Tom Lehrer when introducing "The Elements", a song which lists the chemical elements (at least, those known at the time) "set to a possibly recognizable tune".
Tom Lehrer: This may prove useful to some of you someday, perhaps, in a somewhat bizarre set of circumstances...
- Dungeons & Dragons:
- 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 Eberron setting collect information constantly, just in case some bit of it comes in handy later.
- In the New World of Darkness Tabletop RPG, Encyclopedic Knowledge, 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 Old World of Darkness 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.
- Done in Banjo-Kazooie. 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 answer to each question is different and changes with each playthrough of the game. So getting Brentilda to give you the facts becomes necessary each time you play.
- 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 at the end your character shoots a portal into the moon, thereby sucking the BBEG into space.
- In Final Fantasy II, 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 Final Fantasy VII 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 can use megaphones as weapons, so you can pick it up if you remember to search the locker again.
- In RuneScape, one sidequest, Mahjarrat Memories, gives you an Engrammeter as a reward. Kharshai states at the end of the quest that he wonders what would happen if you were to use it on Freneskae, although he then goes on to say that he fails to see any situation in which you would go there. Guess where you end up going in the (sort of) sequel to the quest?
- In Fatal Frame 4, Ruka's mother taught her a specific song on the piano and it is one of the few memories she has from her childhood. It turns out to be vital, because it is the sacred Tsukimori Song, the only thing capable of defeating Sakuya.
- In Policenauts, local explosive expert Redwood challenges the main character Jonathan to guess which of the two wires - red or blue - must be cut to defuse the bomb he built. Jonathan guesses red "for Redwood", only for Redwood to chastise him for believing that a bomb-maker will always stick to their usual methods. Half game later, Jonathan is put in a similar situation, and he's specifically reminded of Redwood's words. The player, however, must remember that Redwood repeatedly lies to Jonathan. Since he built the bomb, the correct answer really is "red for Redwood".
- Parodied in Oglaf with a royal adviser who's really obsessed with building a labyrinth for the King under this logic. The annoyed King tells him that's stupid and they have no possible need of a labyrinth... at which point a guard runs in and tells the King that his wife has given birth to a monster...
- Whateley Universe:
- Phase is Crazy-Prepared 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 (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 at 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 Crazy-Prepared or a Sheltered Aristocrat. 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...
- Happens twice on Futurama. In one case, Fry's knowledge of 20th-century TV is what saves the Earth from a horde of invading aliens (they wanted to see the final episode of a 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 Megas XLR.
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 The Simpsons's "Treehouse of Horror V", Homer recalls the advice his father gave at his wedding: namely, explaining the Butterfly Effect in the context of time travel and warning Homer not to touch anything.
- In Pinky and the Brain, Brain is on a game show, and Pinky annoys him by chatting in his ear. Pinky is about to talk about The Honeymooners when Brain silences him. The final question, worth everything, is about—The Honeymooners. This is probably a Shout-Out to an episode of The Honeymooners where something similar happens.
- Dave the Barbarian
- "Termites of Endearment" Dave refuses to practice sword fighting because he's busy making decorative knick-knacks for sale. His sister Fang badgers him to practice fighting, and Dave says "one day my love of decorative knick-knacks will one day save us all!" He keeps saying this throughout the episode, usually directly to the audience. Then the Monster of the Week attacks, defeats everyone easily, and is about to kill them all—when Dave notices the monster's bracelet. The monster and Dave agree to knick-knacks together.
- 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?)
- Teen Titans. 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 Rocky and Bullwinkle: 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 Kim Possible 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. Trapped in TV Land 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 Darkwing Duck's origin stories, the phrase "It could come in handy someday," is uttered by:
- There's a Peanuts animated cartoon in which Charlie Brown becomes a spelling bee whiz due to only getting words like "failure".
- Who Wants to Be a Millionaire?: 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 $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.
- Quizbowl. Being a repository of completely random knowledge is an immense asset. Subverted by the 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.
- 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 that are basically set up to encourage this.