When the Mad Scientist or Gadgeteer Genius creates a machine of diabolical nature, some function gets thrown into the mix that wasn't quite planned, doesn't really serve any practical purpose, and may even be an Achilles' Heel- a lever for flooding the cockpit of the Humongous Mecha with its fuel reserves, for instance.
A variant has additions made which do serve a practical use- just not ones which make logical sense for the machine to have: a jetpack that makes martinis, for instance.
Expect Lampshade Hanging to ensue.
See also Fridge Logic.
Compare Oven Logic, where the oven dial goes up to thousands of degrees. One has to wonder why the oven had a dial that could go up that high if it wasn't meant to be used that way.
Compare with Cow Tools, where nothing about the machine makes sense. Contrast with Mundane Utility, where simply being what it is lets the device do something useful- cooking popcorn with your Death Ray, for instance. Frequently overlaps with Self-Destruct Mechanism. See also Caps Lock, Num Lock, Missiles Lock.
In Dual! Parallel Trouble Adventure, Mr. Sanada frequently designs machines with large buttons that you think would activate them, he even coaxes the person to press the button/presses the button himself, before revealing that it doesn't actually do anything. 'It's actually' *Mitsuki sits down on a lever* 'that lever..'
When Takarada of Kill la Kill tries to fight using crab-like Powered Armor, Sanegayama beats him by shoving his shinai up a hole on the back that seems to not only go straight to the unprotected cockpit, but straight up Takarada's ass. What purpose such a structure could have served is never even asked.
Played with in Meanwhile. The Killitron is a doomsday device built by a mild-mannered inventor with no Omnicidal Maniac tendencies whatsoever. However, it turns out that it can be used to manipulate entropy, allowing for such miracles as reversing the aging process and transmuting food and water.
Inverted in Atomic Robo, when Robo's shocked at the lack of extra options:
Robo: Relax. All we have to do is Reverse the Polarity and everything'll go back to... normal. [...] There is no reverse. How could they not include a reverse?! That's just criminally negligent with the kind of ludicrous stuff we get up to around here!
Films — Animated
Monsters vs. Aliens: The latte dispenser is operated by a Big Red Button that is identical and right next to the button that launches all of the US's nuclear missiles.
At the end of Bride of Frankenstein, the enraged Monster is rampaging through the lab. As he approaches a very large wooden lever Dr. Pretorius shouts, "Don't touch that lever! You'll blow us all to atoms!" The question must be asked: if you were collecting all the supplies and fixtures you'd need to build your super high-tech lab, how far down the list would "a lever that will blow us all to atoms" be?
In The Cabin in the Woods, the agency has a big red button that releases all of the monsters they have stored up and no safeguards at all, other than a plastic covering.
The Chompers in Galaxy Quest, Gwen lampshades how ridiculous it is that there is a Death Course in the middle of the ship.
Gwen: Screw that! I'm not doing it! This episode was badly written!
In Spaceballs, Spaceball-1 can go to "Ludicrous Speed", which everybody except Dark Helmet realizes is something they shouldn't do. Fortunately the ship is also equipped with a hand-operated "Emergency Brake" which is labeled "Never Use".
In Die Another Day the villain has a suit that he can use to shock people. For reasons that are not entirely clear, there's a button on the front that causes it to electrocute the guy wearing it.
Discworld has Bungling Inventor "Bloody Stupid" Johnson, who has added quite a number of useless and dangerous things to his inventions.
In Hogfather he added some things to the bathroom in Unseen University that Archchancellor Ridcully would come to regret.
He also designed a nice, upper class neighbourhood that just happened to break the laws of space and time. You can just throw the trash out of the window into the yard, since it's probably not your yard, anyway. It's also has a very low crime rate, as thieves generally prefer to break into one house at a time.
Or the post office sorting machine, which included a wheel with a circumference-to-diameter ratio of exactly 3 (rather than the usual three-and-a-bit, which he thought was untidy), and which soon started sorting letters before they were written.
And his pipe organs usually include special sound effects such as thunder or animal noises, with at least one example also being connected to the building's plumbing system. The UU organ, located in the middle of a city with a million inhabitants, also includes a pipe that plays the Brown Note so loud that it causes earthquakes.
The Hitchhikers Guide To The Galaxy features the Sirius Cybernetics Corporation, a company built entirely around this concept. In the words of the Guide itself, their corporate strategy is based on building devices whose "superficial design flaws completely mask their fundamental design flaws." In other words, you get so involved in getting the thing to work at all that you completely fail to realize that it's incapable of doing what it was made to do in the first place. From the first book alone, examples include a superintelligent robot with a suicidally depressed personality and an intelligent drink dispenser that, no matter what you ask for, always gives you exactly the same horrid concoction that is "perfectly tailored to your individual tastes."
Live Action TV
An episode of Sesame Street involved a high-powered air conditioning system being installed in the Furry Arms Hotel. Humphrey specifically states that it's only meant to be turned up to 10. If the knob is turned up to 14, it will break. Those are literally his exact words. Guess what the resident penguins end up doing.
Far Out Space Nuts: "I said lunch, not launch!" Maybe those two buttons shouldn't be right next to each other?
An episode of Star Trek has Kirk being court-martialed under suspicion of accidentally ejecting an "ion pod" with a crew member still inside it. The prime evidence is (falsified) footage of the bridge during the incident, which includes a closeup of the arm of Kirk's captain's chair, which has three buttons on it - presumably the three things it was determined a Starfleet captain needed to be able to do at any time: "Red Alert," "Yellow Alert," and "Eject Pod."
Davros, the Mad Scientist who created the Daleks on Doctor Who decided that it would be a good idea for his mobile life support system to have a clearly marked on/off switch on the panel in front of it.
In the video for "Rocking The Suburbs" by Ben Folds, the audio fidelity notably drops at one point. Cut to Ben and the video's director ("Weird Al" Yankovic) at a mixing board, whereupon the director improves the audio quality by turning down the Suck level on the mixing board.
The gnomes of Dragonlance. Their inventions seem to start with an idea, then modify as they go to fix perceived problems in ways that seem reasonable until you look at the whole. Some examples:
Falling into water while wearing heavy plate armor tends to be inconvenient. Wouldn't it be nice to take the armor off in a hurry when you need to? So it's set up to be removed quickly. If you fall into water, you might be a little panicked, so the way to remove it should be easily accessible, right? Bright red painted crash bar on the front. And plate armor - especially gnome-modified plate armor - is going to be expensive, so you want a way to retrieve all the pieces if you do need to remove it like that, so... all the pieces are attached to the belt with wires so you can easily find them.
A gnomic effort to light their caverns involved piping magma through them. When this made the average corridor hot enough to flash-fry gnomes, they poured water on the pipes. The net result was that it was still impossible to see because when you pour water on a tube of magma, you get huge quantities of steam. And it was still hot enough that you wouldn't want to spend too long in the corridors unless you were literally a fire elemental. But by the gods it was lit!
In Paranoia, pretty much anything that comes out of Alpha Complex's R&D labs for testing during a Troubleshooter mission.
Dwarf Fortress has a fondness for these, with players often ending up with levers that serve no purpose but to flood parts of their own fortress with lava. This is particularly pronounced in games when players swap out between years so that no one knows what the lever actually does and building around it. For example, Boatmurdered had a lever that, when pulled, flooded a siege workshop. It turned out it had originally been put in to irrigate the farms and became hilariously useless later when someone built a siege workshop on them.
In Advance Wars: Black Hole Rising, Lash proposes to the more practical Hawke that an airport she just finished for him be equipped with add-ons like a self destruct sequence.
Between the two Portal games, there are several examples, all designed by Aperture Science's Cloudcuckoolander founder.
The fuel system de-icer is also a sentient, malevolent AI that can slowly flood the facility with massive amounts of "deadly neurotoxin" stored in a large tank.
A portal gun capable of warping space was originally designed for use as a shower curtain.
Turrets that are sapient, and capable of feeling pain
Empathy Generators on the turrets. To keep them able to shoot people, they also installed an Empathy Suppressor.
Aerial Faith Plates are basically catapults that can propel the player vast distances. Their intended use was to load cargo onto trucks, despite the fact that the cargo is thrown with such force that it breaks and/or bounces back out.
Propulsion and Repulsion Gels, which were originally conceived as dietary aids despite the latter containing an element that "does not like the human skeleton."
And finally Conversion Gel, which literally just paints surfaces white so portals can be put on them. Any old white paint would have sufficed, but no, Aperture Science felt the need to make the white pigment out of crushed moonrocks, complete with implications that a major character developed terminal pneumoconiosis as a result of this. And the recipe for it? It has a huge importance for the game's last battle.
In Kingdom of Loathing, the clan VIP room's shower temperature can be set so low that it makes shards of ice rain down on the user. When you use it, your character questions why someone would even make something like this.
Applies to so many door-lock minipuzzles in all sorts of games. Why would a supposedly everyday door require people to go through lengthy, complex manipulations to get through — the users would get fed up. Why would a door be locked with a device that is disassembled when unlocked, or otherwise only good for one use.
Awesomemod (a mod for The Sims 3) has a configuration setting called "ExplodeInBFBVFS", which allegedly causes your game to explode in "a big fiery ball visible from space". All it really does is display a funny message when you try to run the game, and then immediately quits.
Chrono Trigger In Ozzie's boss battles, you win once the correct switch behind him is hit. The fact that he always has at least one switch that opens a trap door under him is what qualifies him for the trope.
In Barbie: Life in the Dreamhouse, Barbie's Master Computer, Closet, has a button that can change it from a helpful servant, to a power-hungry tormentor. No one among Barbie's gang can remember why Closet has such a button, not even its inventor, Ken.
The artistic variation shows up here, in Starslip. Vanderbeam, alone on the ship, is trying to calm down and forget about ghosts, so he goes around looking at art. He looks at Edward Munch's The Scream, Henri Fuseli'sNightmare, and Hox Torvus'Vanderbeam Getting Eaten By A Ghost, prompting this:
Vanderbeam: Heavens, why did I ever commission this piece?!
Ferb: You know, in retrospect I questioned the inclusion of a self destruct button in the first place.
In "Across the 2nd Dimension" Doofenshmirtz mentions he once deployed an army of robots and hid the self destruct buttons on their feet. Guess how the robots were defeated.
In one episode, Doofenshmirtz spends an entire episode looking for an on-off switch so he can activate his latest -inator. It turns out that all the -inator does is open the cage that he had trapped Perry in.
In one episode Doofenshmirtz builds a Go-Away-Inator which spins a wheel of locations and sends whatever it's pointed at away. Near the end of the episode it sends a group of people into Doof's pants. It turns out that that "My Pants" setting was there because the -inator's wheel had been mixed up with his dry cleaning wheel.
In one episode of Eek The Cat, a professor built a rocket ship to Jupiter, and he told the astronauts that before launch they must make sure the absurdly huge switch is set for Jupiter and not the sun. One character asked, "Why is that even there?"
When the evil Leena is trapped in her own prototype, the De-pruner, her coworkers hit the "decapitate" button.
Leena: I knew I shouldn't have added that option.
Dilbert also installed a voice-operated temperature changer in the shower. Which reacts to any number he says, regardless of context. Dogbert is disappointed to find he himself cannot change the temperature when Dilbert is taking a shower, but he can ask about "That movie with the crazy computer..." "You mean '2001'?"
A Halloween special features an murderous Krusty doll: "Yep, there's your problem. Somebody set this thing to evil."
In a later episode, Bart sets a bunch of Roombas from "off" to "malevolent sentience". They promptly go on a mini-rampage.
Megas XLR: Sometimes Coop can't even make sense of his own designs. Some examples:
Megas has 3 buttons labeled "Destroy the world", "Smite the world" and "Destroy the world, worse", and one button labeled "Save the world". Guess which button is needed? Guess which one is missing from the control panel?
Megas is low on oil in one episode, so Coop literally wrings the grease out of several cheesesteak sandwiches directly into a small tube that refills the tank. The gauge goes from "Empty" —> "Need a little" —> "Almost There" —> "Enough" —> "No really, I'm fine" —> and "PLEASE STOP!"
Recurring teenage villain Cree explained that the only reason she escaped from a prison spaceship was because one of the pilots accidentally pressed the "Blow Up The Engines" button during a fight over trading cards.
Cree: Who else but a bunch of stupid kids would put a "Blow Up The Engines" button on a spaceship?
In anonther episode, the ice cream Monster of the Week is defeated when Numbah Three turns on the heater in the ice cream factory. Quote The Delightful Children From Down the Lane:
DCFDL: A HEATER!? Who puts a HEATER in an ICE CREAM FACTORY?!
He-Man and She-Ra's Christmas Special shows Orko lauching a rocket thats manipulated by one easily breakable lever.
Futurama had Professor Farsnworth's glow-in-the-dark nose making machine. About halfway through the episode, he prepares to insert a note from Leela's parents into it to analyze it and hopefully translate it. This exchange took place:
Fry: Isn't that the machine that makes noses?
Professor: It can do other things! Why shouldn't it?
In one episode of Adventures in Care-a-Lot, Grizzle takes over Care-a-Lot using the Caretaker II, a belly-badge-stealing ray that can turn invisible. Naturally, it gets lost while invisible, and while looking for it, Grizzle warns his minions not to press the blue button that releases all the belly badges, complaining that he never should have installed that button.
In "BOT," the The Transformers episode considered the worst in the TF franchise's 25-ish year history, one of the many, many, many nonsense moments was the solution to the Decepticons' superweapon: a human-level button (on a machine that supposedly had to be controlled by Bruticus, who towers above your average TF, which is why the entire episode was about finding all of Bruticus' scattered parts) clearly marked "Over Load." Yes, two words. You push it, the thing overloads and explodes. (Oh, making a device so big you supposedly can't use it yourself? Not much better. Like we said... it was bad.)
Parodied by Cartoon Network with a Birdman short (link here). Falcon 7 asks why Birdman allows Avenger on his console, while Birdman insists he's "fully-trained" and demonstrates by ordering Avenger to press the Coffee button...which is right next to the Doomsday button. He gets the coffee, but accidentally hit the Doomsday button too.
Iron Man: Armored Adventures: Killer Shrike's flight tech is directly linked to his wrist blasters. After Iron Man smashes the blasters, he points out to the plummeting villain what a bad idea that was.
In American Dad! Stan dies and goes to Heaven, and tries to use his gun to threaten people into sending him back to Earth. Everyone laughs at the idea that they could be harmed in Heaven, until Stan steals an Angel Gun which can kill anyone. As he runs out, one guy questions why they have those.
Many heating devices can reach temperatures far beyond the point where they stop being useful. Some hot tubs get hot enough to kill people, while some toasters get hot enough to burn all toast.
Car speedometers often go higher than is safe to travel in the car in question. In some cases, the speedometer is even designed to read velocities that the car isn't even capable of reaching under normal circumstances. Mostly this happens because there is just one type of speedometer which has to cover a whole range of cars.
Volume controls often go much higher than is ever practical. In some cases, this is simply to prepare for uncommon usage, while in other cases, maximum volume would actually blow out the speakers.
One desktop PC keyboard from around 2000 had special keys to turn the computer on and off, so you wouldn't have to reach down, fumble for the switch, etc. Of course the keyboard drew its power from the computer, so the "On" key never worked. The "Off" key didn't have that problem, but it was in the upper right corner, and thus very easy to hit by accident.
An inversion of this contributed to the Apollo 13 accident. While emptying a cryogenic oxygen tank using a heater, the dial used to watch the temperature did not go above the expected maximum, and as a result no one knew that the temperature was getting significantly higher and damaging some equipment.
Tandy computers had a button that functioned as "Escape" (ESC) on modern computer setups, only it was called "break", because it broke whatever loop a program was stuck in. On the Tandy Color Computer 3 it was even bright red, leaving many uninformed users to be terrified to touch the button for fear the button was something that would break your computer. ("Break" is still on your keyboard - it's usually a secondary function on your "pause" key.)
The first incarnation of the Apple II computer had the "reset" button right above the "enter" key. Since the "Enter" key is pressed more often than any other key, and the "reset" button will instantly hard-reboot your computer, this caused some problems.
Military equipment typically comes with a scuttle mechanism to destroy it when capture is imminent (generally by triggering a thermite charge - the "scuttle charge" - on top of the case). This is occasionally confused with the "Battle Short" switch on military equipment which may conceivably be used as a scuttle mechanism, but that's not its primary purpose: what it does is short out all the breakers and governors, allowing you to run the equipment over its rated maximum power. This is useful in combat when having your equipment overload is preferable to getting hit with high explosive, but if you leave it engaged in other circumstances you are likely to have a bad day.
Zawinski's Law of Software Envelopment - Every program attempts to expand [its features] until it can read mail. Those programs which cannot so expand are replaced by ones which can.