People not thinking things through in comic books.
- Archie Comics' Sonic the Hedgehog: At the end of the Mega Man crossover, Eggman is so outraged that Sonic has ruined his plans for the Super Genesis Wave that he deliberately interferes with Sonic's Reset Button attempt, declaring that he would rather let reality be destroyed than let Sonic restore it to the way it was. Not only does his interference directly result in a Cosmic Retcon, but the residual energy left behind by the Super Genesis Wave ends up ripping the planet Mobius apart and awakening Dark Gaia, leading into a Sonic Unleashed adaptation. With all of this, Eggman admits that his actions were "a bit hasty."
- Batman villain Warren "Great White Shark" White successfully pleaded insanity to escape embezzlement charges. He was sent to Arkham and wound up at the mercy of Gotham's worst psychopaths. Oops.
- During the famous "A Death in the Family" storyline from 1988, the Jason Todd Robin is betrayed to the Joker by his own mother, who is caught up in one of the Joker's criminal schemes. The Joker proceeds to beat Robin nearly to death with a crowbar, only to have Todd's mother ask "What is Batman going to do when he discovers what you've done to his little friend?" Joker's reply is a sullen and subdued "Haven't thought of that..."
- In one issue of the Batman: The Brave and the Bold comic, Nightwing leads the Robins from other points in time (Jason Todd, Tim Drake, Stephanie Brown, Damian Wayne and Carrie Kelly) to one of Ra's al Ghul's bases in order to use a Lazarus Pit to save Batman's life. When they encounter the League of Assassins, Damian leaps out, demanding that they stand down as is his birthright as an al Ghul. The assassins look at each other, then charge at the Robins. Damian then remembers that he's not born yet.
- In an episode of Bruchbach Serenade, Rick has just finished his summer job at city hall. In order to maximize his earnings, he had made the mayor give a speech that made fun of the audience and incorporated Nazi phrases, so he could sell the audience rotten tomatoes. Now the people in charge refuse to give Rick a certificate for the job.
- During the Civil War arc, Jennifer Walters was outed as She-Hulk (again) by a New Warriors hate site. On the way into her office through an angry mob to help some former New Warriors keep their identities hidden from the public, one of the mob recognized her, grabbing her by the arm and ripping her shirt, proudly exclaiming "I've got She-Hulk!" Jen shifted and hoisted the guy up by his lapels.She-Hulk: Alright, you've got She-Hulk! Now what?!
Angry Citizen: I...uh...guess I didn't think this through...
- The undoing of many Diabolik one-shot villains, as their plans tend to have a flaw that Diabolik or Ginko can exploit. Case in point, the copycat who recycled Diabolik's plans and had them executed by lesser thieves: while he had planned for Diabolik to track him down planning to kill him he completely forgot about his accomplice and lover Eva Kant (who, while he was gloating he was about to get rid of Diabolik and take his place, had snuck behind him with some poisoned needles), or that Diabolik rarely reuses old plans because next time Ginko will be ready (he had got away so far because the targets weren't worth of Diabolik, but after establishing the existence of the copycat Ginko was preparing for him).
- Disney Ducks Comic Universe:
- Magica DeSpell in at least two Don Rosa stories, involving her plan to steal Scrooge's #1 Dime, which (as the first money earned by the world's richest man [or duck, whichever]) is the final ingredient in a Midas Touch amulet.
- In "Of Ducks, Dimes and Destinies", Magica travels back to the day Scrooge earned his #1 Dime because she thinks it'll be easier to steal it back then. She gets the dime before Scrooge does- before realizing that, now that she stole it, it is no longer the first money earned by the world's richest man.
- In "A Little Something Special", Magica teams up with the Beagle Boys and Flintheart Glomgold because she sees no overlap in their goals: she wants Scrooge's #1 Dime; the Beagle Boys want the rest of his money; and Flintheart Glomgold just wants to drive Scrooge into poverty and steal his title as the world's richest duck. As Scrooge later points out, his first dime will be of no use for Magica once he's broke, since he will no longer be the world's richest man.
- Doomsday Clock hangs the world's biggest lampshade over Watchmen's ending as Lex Luthor is approached by Ozymandias for help in hunting down Dr. Manhattan. As he does, Luthor recounts Ozymandias' plan for world peace which involved creating an "alien" and causing it to destroy New York in a psychic backlash, forcing world peace, then points out that he never stopped to think of what would happen if they found out the truth, telling him "If you're the smartest person in your world, I'd hate to meet the dumbest."
- During James Robinson's Fantastic Four run, the Quiet Man kicks off a massive plot to turn the public on the FF, aided by the Psycho Man. The Quiet Man plans to open portals to other worlds to flood Earth with demons and alternate heroes and then be seen as the big hero himself by shutting the portals down. Reed tells him to go right ahead and do it...and he can't. As the Quiet Man stands stunned, Reed points out that it may not have been the best idea to hand ultimate power over two worlds to THE PSYCHO MAN.
- Ghost Rider villain Blackout is a half-demon murderer who, in addition to his Casting a Shadow powers, had metal fangs implanted in his jaws to cultivate a vampiric look. In an early encounter with the Ghost Rider, he tried to bite him. Ghost Rider is a flaming skeleton, and the attempt ended with Blackout getting his face badly burnt.
- Johan And Pewitt had this happen in the backstory of "The War Of the Seven Fountains". They stumble across an old, abandoned castle in the middle of a wasteland, and that night are met by the ghost of its former king, who explains that the reason the kingdom disintegrated was because of his idiotic use of a wish he had been granted by a local witch as a reward for his wise rule. Unfortunately, while a great ruler in most cases, the king had a love for wine, and the wish happened to be granted during a period where the wine harvest had gone wrong, and there was none to be had for miles. In a spur of the moment, the king wished that the areas seven water springs would produce wine instead of water. You can probably guess why this was a bad idea. When he tried to force the witch to reverse the magic, she instead cursed the springs to dry up completely, leading to the kingdom falling apart and its inhabitants leaving. The king remained behind and died soon after, but was Barred from the Afterlife by his ancestors, and wouldn't be allowed to rest until the springs flow again, which Johan and Pewitt decide to help with (with a surprise assistance from The Smurfs).
- Fixing the springs turns out to be this as well, as distant relations to the king show up and start fighting over the once again fertile land, the "War" mentioned in the title.
- In the Italian comic book Lilith, the Roman emperor Commodus tells the time-travelling protagonist that the only reason he trusts his chamberlain Eclectus, his personal trainer Narcissus and his concubine Marcia is that, being freed people invise to the Senate, they depend on him for everything. When Lilith's interference makes their plot to assassinate Commodus fail, he's not just angry for their betrayal but, as he says in his angry speech to Marcia, their utter stupidity. Especially Marcia's, as she was Christian and, to please her, Commodus had adopted a policy favorable to them (and indeed, the narrative at the end of that issue specifies that Commodus started a terrifying persecution of the Christians after her execution).
- One Marvel Adventures series had Iron Man sneaking into Dr. Doom's castle to rescue hostages. He utilized a stealth suit which rendered him invisible, but in order to maintain this, Tony could not include offensive capabilities in the design. Late in the book, Doom reveals that he knew Tony was there from the moment he snuck in and pointed out the sheer stupidity of using an invisibility suit to try to sneak into the base belonging to the arch-enemy of the Invisible Woman (which naturally, have measures to detect this exact thing).
- In The Mighty Thor storyline The Ballad of Beta Ray Bill, Mjolnir's worthiness enchantment ended up becoming this - for the longest time, Mjolnir had the worthiness enchantment attached as a way to temper and humble Thor as punishment for his arrogant actions. Never once had Odin the Allfather ever consider that there would be someone else just as worthy, as the alien Beta Ray Bill would soon prove to be when he randomly hit the carrying stick that disguised the hammer against the wall in frustration and transformed into Thor. When Odin brings Bill to Asgard, he's shocked by what he sees.
- In the climax of Northwest Passage, Montglave reveals critical information to Simon in the hopes of permanently turning him against his father, Charles Lord. The information is that Simon's parentage is a Luke, I Might Be Your Father situation since Montglave raped Simon's mother at the time of conception. Unsurprisingly, Simon takes a rather dim view of this knowledge and promptly blows Montglave's brains out.
- Subverted in Paperinik New Adventures with the Evronians' master plan to defeat Xadhoom and turn her into an eternal power source for their empire, as they would have to keep her trapped long enough for the Entropiothron to work and Xadhoom is a Physical Goddess who wants them all dead... Except they know she's a mutated Xerbian who hates them for destroying her homeworld and they're using all the survivors as hostages to force her to comply. Then Double Subverted when the Evronian Emperor realizes they've grossly underestimated the fact Xadhoom is the greatest genius of an entire world of scientists with extreme control on her power means she has the mental strength, self-control and willpower to resist the Entropiothron's attempts at making her explode, and then again when the Xerbian hostages, including the finest minds of a planet of scientists who had years to study how to reverse the effects of Coolflamization (an emotion-draining process that turns the victim into a mindless slave), do just that on every single Coolflame on Evron's Planet Spaceship, the end result being that there's now nothing to keep Xadhoom compliant. That was the last day of the Evronian Empire.
- At the end of the first arc of The Powerpuff GIRLS by IDW Publishing, Mojo Jojo plans to hide in a space pod for several months until he's ready to return to Townsville. He then realizes that he forgot to install a bathroom, which leads to him actually saying that he didn't think this through.
- Rick and Morty (Oni): Knowing that the dinosaurs in his island were specifically bred to be subservient to him, Summer dresses up as Rick to rescue him from the angry workers hed abandoned there. She and Morty dont realize that a bunch of huge carnivores would eat them until after it had happens.
- In Runaways, during their first battle against Excelsior, Chase Stein decides to create a distraction by attacking with the Leapfrog's lasers...which quickly drains the Leapfrog's batteries, forcing the Runaways to flee with their highly distinctive vehicle fully exposed (because without battery power, they can't activate the vehicle's stealth mode) making it easy for Excelsior to track them down. Later in the same arc, Chase makes a similar mistake by ripping out one of the lasers to use it against a villain. Since the laser is no longer hooked up a power source...
- Scooby-Doo! Team-Up:
- Multi-Man can destroy himself to return even more powerful and uses it to threaten the heroes. Shaggy brings up the possibility that such power might wear off and he dies for real and Multi-Man admits he never thought about that.
- The Mad Scientist in the Magilla Gorilla crossover didn't think about what he'd do with his experiments before changing his "volunteers"' bodies.
- In the Siege miniseries of Secret Wars (2015), Lady Kate Bishop from the 1600s deliberately gets arrested so she can be sent to the wall and join the Watch for adventures. She later gets hit by a magically-induced epiphany, realising that she's a girl with pointy sticks and she's facing terrible armies that scare God-Emperor Doom himself. And said armies are coming for her through a now disappeared wall...
- Doctor Octopus's plan in the Spider-Man storyline Ends of the Earth. With the evil doc dying, Doc Ock plans to flash-fry the Earth, leaving approximately .08 percent of humanity to live on and remember him as the greatest monster that ever lived. However, Spidey points out a glaring flaw in this plan: they'll live. Brain dead, their brains flash-fried, too. Doc Ock flips.
- In Suicide Squad, former NSC agent Tolliver and corrupt Senator Cray try to get Amanda Waller to get Cray re-elected or they'll expose the Squad to the public. After killing Tolliver, Rick Flagg confronts Cray at gunpoint and illustrates how stupid it is to blackmail a team made up of super-villains.Flagg: When you set out to blackmail the Squad, Senator, didn't you realize you were trying to coerce thugs and killers? Ruthless people. Didn't it ever occur to you that the easiest way of dealing with you was to kill you?
- Supergirl: Some of her adventures provide good examples:
- In Red Daughter of Krypton, Supergirl used her heat vision on a blood maelstrom conjured by Atrocitus, and accidentally burned half city down instead of destroying the maelstrom.
- In Supergirl: Cosmic Adventures in the 8th Grade, villain Belinda Zee uses her "Superior Vision" on Streaky (Supergirl's pet cat), and accidentally turns him into a sabertooth tiger.Superior Girl: That was not my best plan.
- In Supergirl Volume 5 #3 Supergirl decides to fight Lex Luthor alone. Quickly she realizes her plan is not a brilliant one.Supergirl: Two seconds and I know. I'm in way over my head.
- In Supergirl #20 — a tie-in to the reviled Amazons Attack storyline — she and Wonder Girl hijack Air Force One because they think they could end the war by making the President sit down in the same room with the Amazon Queen. When things went south very, very quickly she realized that it was a big mistake.
- In Supergirl Annual #2, Brainiac 5 was analyzing how a mystical statue reacted to different kinds of energy, and he accidentally turned it into a kind of super-bomb. He admitted that it was not a very good plan.Brainiac 5: Its a ten-thousand-year-old Brocian hunting statue! Rumored by natives to have "magical" properties when struck by lightning, so I was analyzing its reception to other kinds of energy!
Supergirl: Okay! So what did you hit it with?
Brainiac-5: Uh, I opened the timestream and bombarded it with chronon energy.
Brainiac-5: Obviously that wasn't the best of my ideas!
Supergirl: So what's it doing now?
Brainiac-5: Based on my readings, I'm pretty sure I just created a magical time bomb. And if my calculations are correct, we've got less than four seconds to live.
- In Superior, demon Omron tricks young Simon into trading away his soul to become the super hero Superior. With time winding down before his deadline to avoid being thrown into the depths of Hell, Omron celebrates his first soul...until friend Madeline points out the problem: Omron has made Superior into a being who is, for all intents and purposes, immortal. And if Superior can never die...then how is Omron going to collect his soul?
- Krypton No More, super-villain Protector wants to defeat Superman... so he bursts into the Fortress of Solitude and attacks both Superman and Supergirl. He gets his butt royally kicked and has to run away at the first opportunity.
- In War World:
- Alien overlord Mongul blackmails Superman into retrieving a special key. Superman intended to play along, retrieve the Key and then try to thwart Mongul. Unfortunately, Superman had no plan ready to handle him.
- When Supergirl and Superman face up to the super-weapon Warworld, Superman decides to play decoy to test Warworld's missiles' power. Right before being hit by one of them, Superman realizes that massive thing can kill him.
- Superman villain Doomsday was created through this - his creator, the scientist Bertron, sought to make the Ultimate Life Form and spent three decades constantly murdering a baby and having it cloned over and over again. He honestly had no idea what to do when he actually survived to reach that level. Or the fact that its deaths were genetically imprinted into him and he sought revenge.
- The Superman Adventures: In one of the one-page stories featured in Issue #41, Mxyzptlk tries to get around the saying his name backwards issue by pulling Superman into his dimension instead of going into Superman's. Superman simply says "Namrepus" twice and goes back home. Mxy's girlfriend even comments that he's "really got to start thinking these plans out better".
- A secret cabal of criminals in Metropolis has a member who's setting fires as part of an insurance scam. He bribes a kid to say Superman did it, claiming it'll be a good distraction. His boss chews him out for honestly thinking anyone in Metropolis is going to believe Superman is going around setting fires for no reason. By trying to make it look that way, the guy has simply ensured that Superman and the fire department realize something is up and start looking for the real arsonist. Indeed, the kid makes the accusation and after a bit of worrying, realizes he's lying about it. Even the kid is told he messed up by actively lying to law enforcement.
- That same guy is killed by an enforcer who drops him from the sky in the middle of Metropolis. The cabal's reporter ally immediately tries to put together a "SUPERMAN MURDERS MAN" front page for The Daily Planet. Perry White's response to her attempt can be summed up as "so Superman, for no reason, kills a low-level thug in broad daylight in the middle of the city? And the only "proof" is eyewitnesses seeing a red blur which could easily be Bizarro, a shapeshifter or a dozen different flying people in costume? And somehow, Superman did all this when he was on film helping the Justice League fight Starro across the country at the same time?" Needless to say, the story does not see print.
- In The Unbeatable Squirrel Girl, Melissa frames Squirrel Girl for attacks involving animals in New York. Even when she's beaten, Melissa gloats Doreen will never be able to prove herself and Melissa will get away with it. At which point, the cops are hit by numerous messages from just about every other hero in the Marvel Universe speaking up for Squirrel Girl and how they know she's innocent. It never seemed to occur to Melissa trying to frame someone so loved in the super-hero community was a bad idea.