Someone does something that puts them, or the people around them in a bad or unpleasant situation. Hindsight reveals that although they had good intentions, their actions were not in their best interests.
If questioned about why they did it, they'll often respond with the reason for everything that has ever been done by anyone at any time and any place: "It seemed like a good idea at the time!".
This is also used sometimes as an explanation for Chaotic Neutral or Chaotic Stupid actions. Contrast I Did What I Had to Do, which does the same as in this case, but for Lawful Neutral or Lawful Stupid actions and their moral, rather than strategical, consequences. Often goes hand in hand with Alcohol-Induced Idiocy for obvious reasons. If the plan somehow still works—and is stated or implied to work not despite but because of how ridiculous it seems—that's Refuge in Audacity and/or Crazy Enough to Work.
- In one commercial for Jameson's Irish Whiskey, John Jameson leaps overboard when one of his barrels of whiskey is lost in a storm to retrieve it, and while he's down there narrator says "In hindsight, that probably wasn't a good idea" when he sees a giant octopus start reaching towards him. Viewable here.
- In another, as a fire ravages Dublin, he grabs an ax when the fire reaches his distillery. The narration says "John Jameson devised a brilliant plan. But there was simply no time, so, he devised another, less-brilliant plan." Said not-so-brilliant-plan is chopping open a sluice gate of a giant, stone dam to flood the city. Full version here.
- The scientists of the Open Sado Project in 7 Seeds. One of them discovered a new type of Lizard Ant, who seem partial to the energy bars that the scientists eat themselves. One of their later hologram-recordings mentions that the ants escaped their original glass nest and are roaming around freely, with some of the scientists hallucinating. It's not exactly clear how many years passed between this event and when our protagonists finally encounter it, but by the time they do, the facility is a mess of huge holes, filled with these and other huge ants and even larger earthworms and they all suffer from hallucinations which makes them disorented. And this is all cause the scientists were doing their job, trying to continue regular life of scientists in a facility meant to replicate the world for the protagonists whenever they awaken after The End of the World as We Know It.
- Pokémon: The First Movie. Maybe don't create the world's strongest Pokémon to use for your own personal gain/world domination without any way to control it. Also see Gone Horribly Right.
- The corrupt World Government in One Piece admitted privately that they made a major mistake with the Whitebeard War. They managed to capture the late pirate king Gol D. Roger's son Portgas D. Ace, and wanted to not only end Roger's bloodline but also use Ace as bait to draw in Whitebeard so they could defeat Whitebeard and his crew. Unfortunately, several outside factors made things go south very fast. While the World Government had no control over the outside factors that turned what should have been a great victory into a Pyrrhic Victory, it should have been obvious to the World Government that things wouldn't go down so simply, to say nothing of the fact that they really didn't consider the ramifications in the long term. They admitted they only wanted Ace dead because of his parentage, not because he was particularly threatening in and of himself. Whitebeard was on life support and would have died anyway in a few more years. In short, the World Government attempted to fix a problem that was already going to be solved anyways, and ended up bringing far greater problems as a result.
- Ace's brother Luffy tried to rescue him at the super prison Impel Down. When that didn't work, Luffy made a huge jail break that ended up releasing some of the most dangerous prisoners in the world. The Government's reaction to that was to cover it up so they wouldn't lose the people's faith, despite the fact that if such prisoners start something (which they will), the escape will be exposed anyway and the government will lose face for both the escape and lying to the people.
- Taking down Whitebeard created a power vacuum and disrupted the delicate balance of power among the strongest and most influential groups of pirates in the world. After the war, so much of the government's forces were stretched thin that the government could barely keep a lid on the ensuing chaos.
- While they did succeed in beating Whitebeard, with his final breath, Whitebeard confirmed that the world famous treasure that belonged to Roger and that everyone was looking for did in fact exist. Fleet Admiral Sengoku reacted with a look of both fear and rage when Whitebeard did this, as he knew that with the word out, more pirates would now venture out to find One Piece, and an even bigger and more chaotic age of piracy would begin. With his final breath, Whitebeard basically invalidated every aim the World Government had by starting this war, making all of the Marine's spent resources and sacrifices a complete waste.
- The biggest blunder of all was the arrogant view of the World Government that Whitebeard was just another pirate, albeit a very powerful one. Whitebeard was far more than that to many people, and it was the respect he commanded from others that caused Red Haired Shanks to make sure that Whitebeard and Ace would get the burials they deserved. The World Government couldn't even put the heads of both Whitebeard and Ace on display as a warning to other pirates like they wanted to.
- Supergirl extradited her enemy Reactron to New Krypton illegally so he got trialed and punished for his crimes (something Earth justice courts seemed unwilling to do). Nonetheless, Lex Luthor had turned him into a ticking human bomb which blew the planet and the Kryptonian race up. In Bizarrogirl storyline, Kara is still blaming herself for it, stating: "I thought I was doing the right thing."
- Said word for word by Story!Loki in issue #16 of Loki: Agent of Asgard when their best (and only) friend began to question why they turned her soul into a piece of magical jewellery. Come to think of it if you apply this reasoning to most of young Loki's plans they begin to make a strange amount of sense... sometimes they even work.
- In White Sand, Kenton spends a long time arguing to be allowed to take the Mastrell's Path exam, but when he enters the arena, his first thought is "remind me again, why did I think this was a good idea?".
- From Attack of the Teacher Creature:
Hobbes: I'll pass, thank you. I'm not interested in that stuff. I didn't sell my soul to the devil.Calvin: Neither have I.Hobbes: Yes, but you nearly did once.Calvin: Well, it seemed like a good offer!
- In Bitter Tears: An Anon-A-Miss Fic, this is the best Scootaloo can come up with when she's asked why she went along with the Anon-A-Miss scheme. Rainbow Dash is rather Disappointed by the Motive when she finds out, saying that at least Apple Bloom and Sweetie Belle had a flimsy motivation with jealousy over the attention Sunset Shimmer was getting from their sisters; Scootaloo doesn't even have that.
- The main plotline of the fic, "It Seemed Like A Good Idea At The Time" by Livin4Jesus. It features Clint and Tony getting drunk and doing dumb things.
- American Outlaws
Jesse James: A war against the railroad... what the hell was I thinking?Frank: Well, I'm sure it seemed like a good idea at the time.
- Hannibal has this exchange where Mason Verger explains how he ended up in his current state, with some help from some drugs Lecter gave him during one of their "therapy sessions":
Mason Verger: The good doctor approached me with a piece of broken mirror and said...[Flashback: Lecter is holding a shard of broken glass]Hannibal Lecter: Try peeling off your face...Mason Verger: ...and feeding it to the dogs. [Flashback: Verger peels his face off.] Well, it seemed like a good idea at the time.
- Jesse Stone: No Remorse. Jesse Stone suggests Dr. Dix take up fishing.
Dr. Dix: I hate fishin'.Chief Jesse Stone: So do I.Dix: So why'd you suggest it?Stone': Seemed like a good idea at the time, doesn't cost me anything.
- The 1975 comedy film called, It Seemed Like a Good Idea at the Time, starring Stephanie Powers and John Candy.
- Live Free or Die Hard
Lucy McClane: Daddy, you're out of your mind.John McClane: What're you talkin' about?Lucy McClane: You shot yourself!John McClane: [groaning] It seemed like a good idea at the time.
- The Magnificent Seven:
Calvera: What I don't understand is why a man like you took the job in the first place, hmm? Why, huh?Chris: I wonder myself.Calvera: No, come on, come on, tell me why.Vin: It's like a fellow I once knew in El Paso. One day, he just took all his clothes off and jumped in a mess of cactus. I asked him that same question, "Why?"Calvera: And?Vin: He said, "It seemed to be a good idea at the time."
- The Mummy
Evelyn: By the way, why did you kiss me?
Rick: I don't know. I was about to be hanged. It seemed like a good idea at the time.
- In the Mystery Science Theater 3000 movie, Crow attempts to escape the Satellite of Love by digging a tunnel through space. When asked why he decided to bore a hole through the hull of the ship, he responds, "I calculated the odds of this working vs the odds that I was doing something incredibly stupid and... I went ahead anyway."
- Without a Paddle. Del Knox has spent 30 years in a cabin after partnering with D.B. Cooper in his famous skyjacking.
Jerry Conlaine: But you could've left! Why'd you stay up here all these years?Del Knox: Seemed like a good idea at the time. Know what I mean, kid?
- Solaris (2002)
Chris Kelvin: Why did you kill yourself?Gibarian: It seemed like a good idea at the time, now I think I made a mistake.
- In Mission: Impossible – Ghost Protocol, after the Kremlin explodes, Ethan is taken to hospital and is suspected to be responsible for the explosion. The Russian cop Sidorov is sent to the hospital to investigate, but Ethan manages to free himself and climbs out of the window to jump down into a refuse container, but realises that it's way too high.
Sidorov: Not a good idea.Ethan: Seemed like one three minutes ago.
- The Hitchhiker's Guide to the Galaxy: Everything Zaphod Beeblebrox ever does, except when caught up in a plan related to finding out who really rules the universe in later volumes. Of course, this seems to have been the main reason Zaphod pulled said plan on himself by altering his own memories; even he questions his own judgment on this one.
- In the novel Knight Life by Peter David, Merlin says any question can be answered by one of three statements: "Everybody has to be somewhere," "God told me to do it," and "It seemed like a good idea at the time."
- In Oryx and Crake, where pigs are spliced with human DNA in order to create ultra-large pigs who grow multiple human organs that are used for transplants. Some of them even have some human brain tissue, which makes them viciously intelligent. Of course, it seemed like a good idea at the time.
- Similarly to the Oryx and Crake example, in the Revelation Space universe an intelligent species of "hyperpigs" exists due to genetic manipulations conducted to provide transplant materials. While things are rocky for a long while, a hyperpig ends up being vital to saving all humans and hyperpigs from the Inhibitors.
- Any of Chris's antics during his college career in The Pale King.
- In the Discworld series, Nanny Ogg's primary method of functioning is explicitly described as, "Nanny's philosophy of life was to do what seemed like a good idea at the time, and to do it as hard as possible. It had never let her down."
- A nonfiction book by Bill Fawcett cataloging such events in Real Life uses the trope as its title.
- Harry Dresden cites this word for word when he admits that he may have kinda thrown himself out of a moving car. He had a plan. Sort of.
- The Horrible Histories: 20th Century novel lists a whole bunch of useless 20th century inventions that seemed like good ideas, but weren't. They're even referred to with the acronym "SLAGIATT" - "Seemed Like A Good Idea At The Time!"
- In the opening quote for one of the chapters in The Grimnoir Chronicles, this is the defense offered by the people who accidentally caused the Dust Bowl by magically altering the weather.
- In Warrior Cats, StarClan thought it was a good idea to hide the secret about their parents from Hollyleaf, Lionblaze, and Jayfeather. It wasn't.
- Adam-12: Several episodes where officers — both Malloy and Reed, and then other officers as well — are shown making serious mistakes that seem to work out well initially but later on have not-so-good outcomes or might not have made good outcomes, and an authority figure pointing said mistakes out. One of the most notable examples:
- Malloy making several judgment mistakes in "A Jumper-Code 2," in the concluding call of the episode (a possible jumper on a tall ledge); Malloy makes a high-risk move that, while it works out well, could have gotten either him and/or the jumper killed or badly hurt.
- Sometimes illustrated through the character of Officer Ed Wells, the cocky officer who often acts before he thinks. His attitudes are spelled out perfectly in "A Dead Cop Can't Help Anyone," where the first call we see him work — Wells and his partner barging in on a domestic dispute and narrowly avoiding getting shot — turns out well enough, but a second call (a psychotic gunman randomly firing at passersby in a residential neighborhood) ends with him getting shot as he was running toward the house to try to subdue the gunman. Don't worry: Wells is OK, and he'll be back in the future.
- Young Indiana Jones episode "Demons of Deception" ("Verdun" and "Paris")
Remy Baudouin: I can't believe you actually did that. You could have ended up in front of a firing squad!Indiana Jones: They'll never figure it out.Remy Baudouin: But still, you lost your courier's job, and you put yourself back in the mud. You're crazy!Indiana Jones: It seemed like a good idea at the time. Some men got to live another day.
- The producers of The Amazing Race have been quoted as saying this about the Family Edition.
- On Attack of the Show!, they tested the Sham Wow! and the Zorbees, and used substances such as vomit. Kevin nearly threw up on camera.
- And then they tested the Slap Chop on sheep eyes...
- Comes up in almost each plan by John in Farscape.
- Gossip Girl episode "All About My Brother"
Lily van der Woodsen: Really, Rufus, what were you thinking? You threw her a surprise birthday party and had her face painted on a cake with a tiara?Rufus Humphrey: It seemed like a good idea at the time.Lily van der Woodsen: So did flannel and acid wash-jeans, but they weren't flattering either.
- Lois & Clark: The New Adventures of Superman episode "Tempus Fugitive"
Clark Kent: Glasses, secret identity... seemed like a good idea at the time.
- On an episode of Night Court, Mac’s bigoted grandfather can’t accept that his grandson has married an Asian woman. So Harry orders his grandfather arrested and locks him up in the same cell with Mac’s wife, so the two of them can get to know each other better. Mac is aghast when he finds out, and a crestfallen Harry gives the trope name word-for-word as his defense. Mac responds, “Well, sir, I’m sure human sacrifice seemed like a good idea at the time!”
- In Star Trek: The Original Series, Spock's father, Sarek, gives this as the reason why he married Spock's human mother:
Spock: (about his mother) Emotional, isn't she?Sarek: She has always been that way.Spock: Indeed. Why did you marry her?Sarek: At the time it seemed the logical thing to do.
- Star Trek: Deep Space Nine episode "The Emperor's New Cloak".
Quark: I still don't understand why you'd want to come here in the first place.Zek: Simple, really. I came to find new financial opportunities for the Ferengi people.Rom: In the alternate universe?Zek: Well, it seemed like a good idea at the time.
- The Stock Phrase is also used in "The Way Of The Warrior Part I", when Sisko is rather surprised to find Dukat on the side of the Cardassian Civilian Government instead of Cardassian Military. Facing a revolution, Dukat had to consider what was best for... well, Dukat.
Sisko: In other words, you saw which way the wind was blowing and switched sides.Dukat: It seemed like a good idea at the time.
- Sisko uses the phrase to defend the Federation's No Transhumanism Allowed laws, since genetic engineering produced A Villain Named Khan.
- The Stock Phrase is also used in "The Way Of The Warrior Part I", when Sisko is rather surprised to find Dukat on the side of the Cardassian Civilian Government instead of Cardassian Military. Facing a revolution, Dukat had to consider what was best for... well, Dukat.
- Terry and the Pirates episode "Deadly Species" (1952):
Terry Lee: Good timing, Major.Major Ellis: Oh, it was quite simple. All I had to do was follow the baskets you chaps so thoughtfully pushed off the truck.Terry Lee: It seemed like a good idea at the time.
- Trailer Park Boys episode "Propane, Propane":
Bubbles: You're not really marrying Lahey's ex-wife are ya? [snip]Ricky: Look Julian, I was baked out of my mind, it seemed like a good idea at the time alright?
- One stand-up comedian says that this is the reason why men do so many stupid and idiotic things, because guys aren't thinking about the past or the future and are only concerned with having a good time right now. He uses Bill Clinton as an example, and claims Bill would have gotten off scot free if he had just told the truth.
"Mr. President, are we to understand that she just walked right into your office and started... well, you know.""Seemed like a good idea at the time!"
- iCarly episode "iSell Penny Tees":
Unnamed child: You already pre-paid us. For the whole month. (holds a wad of cash up to Carly and Freddie)Carly: (to Freddie, who looks at her weirded out) ...It seemed like a good idea at the time.
- On Parks and Recreation a young grade-school girl visits the office on a class assignment to learn about government, and finds Ron Swanson to talk with. He happily shares his disapproving views on the government and taxation, and gives her a going-away present of a Claymore mine, telling her "Protect what's yours." Her mother later visits, furious at her daughter being given ordnance, and Ron utters the trope phrase.
- Air Crash Investigation: The root cause of some of the disasters caused by pilot error. "Kid in the Cockpit" concerned a famous Russian case where a senior airline pilot allowed his teenage son to take the controls of a brand new Airbus A310. The teen inadvertently disabled the plane's autopilot and the flight crew, unfamiliar with the state-of-the-art aircraft, failed to bring it back under control. Tragic hilarity ensued. An especially needless tragedy given that the investigators found that everything would have been fine if they had just let go of the control column.
- In the 2nd episode of Malcolm in the Middle, when Malcolm's Mother (who had been interrogating Malcolm and the boys believing that they were responsible for the destruction of one of her dresses) finds out how the boys had been surviving her punishments, Malcolm and the boys get desperate and they attempt to flee once they get found out by creating a tunnel. When their mom (who had calmed down) goes to re-confront them, she finds their room completely destroyed, while Malcolm puts the icing on the cake:
Malcolm: (turns to the viewers) "I swear to god! On paper, this was a great idea!"
- Lampshaeded in an episode of The Drew Carey Show after another screw-up by Lewis and Oswald:
Drew: Everything seemed like a good idea at the time! Lead paint seemed like a good idea at the time! Living under high tension lines seemed like a good idea at the time! Nuclear blasts you could watch seemed like a good idea at the time!
- The song "A Good Idea At the Time" by OK Go both expresses Sympathy for the Devil and is an explicit homage to The Rolling Stones song of the same, portraying Lucifer as simply a guy after a good time who keeps winding up causing horrific situations throughout history, usually because of this trope and the consumption of ludicrous amounts of booze.
- The narrator of "Weird Al" Yankovic's "The Biggest Ball of Twine in Minnesota" quotes this trope verbatim while speculating why the titular twine ball was built.
- The inclusion of 3D glasses with The Raveonettes album Lust Lust Lust must have seemed like a fun gimmick at the time, but unfortunately it rendered the album ineligible for the UK Albums Chart. None of their albums since have charted in the UK at all.
- When he was 21, Tom Lehrer thought it a good idea to write "The Old Dope Peddler". Later, he called the song "Chilling".
- In The Addams Family, Gomez tells the giant squid in the cellar that this is why the United States has the Electoral College. (Used as a throwaway joke.)
- In Portal 2 you're given the opportunity to remove Big Bad GLaDOS' control over the facility and replace her with Wheatley, a cheery, kindhearted robot that's done nothing but help you. Seems like a great idea, right? Well, keep in mind that you should have noticed by this point that the "cheery, kindhearted robot that's done nothing but help you" is in fact an idiot. But the immediate effect is that anyone who gets put in charge of the facility is driven insane (good job turning your only friend into a homicidal maniac) and said friend is actually a literal Idiot Ball; "He's the product of the greatest minds of a generation working together with the express purpose of building the dumbest moron who ever lived." And you just put him in charge of the facility that was taking great effort to kill you before you put a vicious idiot in the driver's seat.
- This statement could probably be the unofficial motto for Aperture Science in general. Which is exemplified by the Mantis DNA project, in which the second batch of test subjects gets used for a new test: fighting an army of Mantis Men.
- A Real Life example for The Elder Scrolls V: Skyrim. Introducing paid mods into a passionate, decades-old community with no prior warning wasn't the most well-thought out plan. Insisting it was for the best intentions didn't help. The feature was removed amid intense backlash mere days later.
- Another real life example. Back in 1988 Nintendo wanted to develop a CD peripheral for the SNES. They first partnered with Sony, but after discovering the deal gave Sony unprecedented control over the games on it, they bailed and partnered with Philips. This made Sony none too happy at the betrayal. The SNES never got a CD add-on, Philips got temporary rights to misuse Nintendo IPs, and Sony got busy preparing for the formal announcement of the PlayStation. Nice Job Breaking It, Hero! indeed.
- In RuneScape, if you tease the bandit "Narf" about his name, he mocks yours (your username) in return, and your character replies that it seemed like a good idea when they were signing up!
- In Dan and Mab's Furry Adventures, the cubi race are mentioned to be the kings of this, due to their emotion reading talents making them very emotional. Fights with them are compared to fighting someone who's blind drunk.
- Colour Wheel: This is why Red gave his robot lasers.
- El Goonish Shive
- Daniel Elliot Shive, the author, says this when asked about the comic's name.
- He also claims Elliot will likely feel this way about "her" decision in this comic. As promised: "It honestly seemed like a good idea at the time."
- In Commander Kitty, while the line itself is never said, it's the title of a strip where the truth comes out about Zenith Central... and in light of what's been revealed so far, it makes absolutely no sense whatsoever.
- In Namesake, Selva explains her plan to prevent people from being brainwashed by poppies, mainly turning them into inanimate objects (since your head can't be infected by poppies if you don't have a head) in these terms.
- In The Order of the Stick, Haley says this about her tendency in older strips to both dungeon-delve with a bare midriff and get into Designated Girl Fights "while hurling offensively gender-charged insults".
Ian: Okay, the important thing to remember is that it seemed like a really good idea at the time.
- When we first meet Haley's dad, he's rotting in a prison. He later admits that he's trying to overthrow the local Evil Empire, and thought that being a Play-Along Prisoner would be a great way to find allies. He hit a snag when it became apparent that breaking out would not be so easy.
- In the Chakona Space 'verse, chakats are mentioned to be highly susceptible to this.
- Red vs. Blue, in episode 52 Have We Met?:
One of the many Churches: So, what did you do?
Yellow Armor Church: Aw, man, it seemed like such a good idea at the time!
- This is a running gag in Prequel, where it's referred to as a "BEST IDEA." Highlights include dismantling a swinging pendulum to use it as a weapon.
- What the Fuck Is Wrong with You? is full of these moments.
- In The Trash Pack webseries episode "Snot My Problem", Trash-A-Pillar and Scummy Screen feel this way when it comes to a link.
Blow Fly: What did you do?!Trash-A-Pillar: Uh, nothing! I just clicked on this little link that said “Download this virus to win one million dollars”!Scummy Screen: (Congested and obviously ill-looking) It seemed like a good deal at the time…
- Milked for all its comedic worth in Family Guy. Adam West rolls around in nuclear waste in order to gain superpowers — and gets lymphoma. The doctor who he explains this to is taking this all in, and concludes that Adam West is an idiot — much as someone would do were this same feat attempted in Real Life. The irony is that earlier in the story, the Griffins had gained superpowers in a manner quite similar, and Adam West's rolling around in the waste was part of a desperate plot to put a stop to their evil dominion over the town. Of course, he still succeeds — the Griffins feel extremely guilty realizing that Adam West got lymphoma just because they were using their superpowers to be petty jerks.
- By technicality that would also make this moment an Unintentional Backup Plan.
- The Amazing Chan and the Chan Clan episode "The Gypsy Caper". Suzie, Alan, Anne and Tom are exhausted, Tom spots a hive and suggests they partake of the honey as a natural energy source. Unfortunately, the bees aren't too thrilled about that and the group ends up getting a second wind by fleeing and diving into a lake.
- In Jackie Chan Adventures
Uncle: (To Jackie) You destroyed the demon! Yin and Yang! Now the world is out of balance! Nobody told you to destroy the demon!
- Jade destroys Shendu's physical form after they beat him at the end of season 1. Unfortunately this allows other forms of evil beings to come forth, since the world NEEDS a Balance Between Good and Evil. The only reason it seems things float towards the good side of things is because said evil is sealed, NOT destroyed.
- It happens when Jackie destroys the talismans. He had hoped that their power would be destroyed and would end people misusing their powers, but unfortunately their powers can't be destroyed; only their hosts (which were the talismans at the time) can. Their powers then sought out new hosts and he inadvertently started the talisman hunt all over again.
- In Drawn Together episode "Breakfast Food Killer", that hiding the UCP codes up his butt seemed like a good idea at the time. Though he didn't really have any other place to hide them.
- In the episode of the Nickelodeon cartoon Rugrats entitled, "Chuckie is Rich", Drew foolishly invests the majority of Chaz's new money into a product that seemed promising...until it failed and the company went bankrupt. He uses this as his excuse.
- Dastardly and Muttley in Their Flying Machines: Every idea Klunk comes up with for the Vulture Squadron to catch Yankee Doodle Pigeon seemed like a good idea at the time. Once it's implemented, Epic Fail is imminent.
- Bob's Burgers - Tina is backed into a corner when classmate Tammy blackmails her with the threat of reading Tina's 'erotic friend fiction' to her crush Jimmy Junior - her mom reassures her, and tells her to take control of the situation and read her fiction herself to the whole class. It's only after she repeats her advice to Bob that she sees what a bad idea it is.
- Squirrel Boy: Andy says something along the lines of this when he mentions that he's been slowly replacing his bedroom door with graham crackers as a trio of rat gangsters are breaking it down.
- In Monsters, Inc., Mike sums this up in a sarcastic rant after he and Sully get banished to the human world.
Mike: Oh, what a great idea going to your ol' pal, Waternoose, TOO BAD HE WAS IN ON THE WHOLE THING!
- During the Three Kingdoms period of ancient China, the Battle of Chibi was a case of this. The warlord Cao Cao, fresh over his conquest of northern China, marched his forces south in order to subjugate the only truly major opposition to his reunification of the whole country: Liu Biao and Sun Quan. Liu Biao died and his successor quickly surrendered, and Cao prepared for war with Sun. His reasoning was sound: his men, while exhausted, were fresh off numerous victories and his forces far outnumbered Sun's. He hoped to intimidate Sun into surrender, or at least breakthrough and force said surrender. The bad idea came from his forces being exhausted from the long march, many of his best generals and officers staying behind to consolidate his new territory, and the fact that the terrain in the south was unsuited for the cavalry tactics he used with such efficiency. A combination of determined resistance, an attack with fire ships, unseasonable weather that made the famous fire attack even more effective, and plague forced his retreat.
- The colonization of New England. Most of the British colonies in North America were set up either as trading posts or as cash cows for profitable crops. New England, on the other hand, was Britain's dumping ground for social misfits and religious dissidents - basically anyone they didn't know what to do with. Massachusetts in particular was a hotbed of political radicals and religious whackjobs for most of the 18th century. Less than a century after its initial colonization, New England became the center of a secessionist movement that would eventually become The American Revolution. Maybe putting all the crazy people in one place wasn't such a great idea...
- The Japanese sneak attack on Pearl Harbor. Japan was several years into its occupation of most of East and South-East Asia but was running low on oil and other vital supplies. America gradually stopped selling Japan things due to outrage over Japan's conduct in the Sino-Japanese war, which drove Japan into even more desperate straights as they tried to invade and secure oil-producing regions in the Pacific. Attacking the American base at Pearl Harbor was supposed to prevent loss of face on the Japanese part, to show the Americans that Japan was not to be trifled with. Instead, it provided an instant and undeniable causus belli for Americans to directly enter a war that had previously been distant and often considered 'not our problem'. Unfortunately for the Japanese forces, America's wartime production massively outdid their own. Naval Marshal General Yamamoto famously said "I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve."
- Hitler declaring war on the United States after the United States declared war on Japan. It may have been a case of Honor Before Reason, as Japan and Germany were allies. Hitler wanted to be able to sink the American ships which were bringing much-needed supplies to England... but he didn't stop to think that the only reason that the United States wasn't doing more than providing supplies was because there was no state of war between Germany and the U.S.
- Mary Renault on the burning of Persepolis by Alexander the Great:
"Like many happenings at a very successful party it seemed like a good idea at the time."
- This was the reason given for the production of The Day the Clown Cried, a movie about a Holocaust-era clown, that will never be allowed to see the light of day until at least 2025 when the copy Lewis gave to the Library of Congress is finally allowed to be screened.
- On Aeroflot Flight 593, the plane's captain took his two children into the cockpit to let them sit at the controls of the brand-new and impressive Airbus A310. The captain's teenaged son, who had no idea how the plane really worked, inadvertently disabled the autopilot. The flight crew, unfamiliar with the state-of-the-art autopilot, were unable to regain control of the aircraft. Flight 593 crashed, killing all 75 people on board.
- Eating large quantities of food, e.g. as part of a contest, may seem like a fun thing to do...until the food coma and wooziness kick in less than an hour later.
- The mega-popular image hosting site Imgur instituted paid advertisements in June 2015. The first company to attempt it was Warner Brothers Records. The Warner Bros Records account had dropped to almost -60,000 reputation in less than a week. They made three whole posts before the account was reset due to this intense negative reception. This was mere days after the forced removal of NSFW comments (which in no way was related to the incoming advertisers, trust us), that sparked a mini-revolt by the community at large. Imgur reinstated NSFW comments as an option that was off by default.
- Fashion trends can sometimes be this, when you look back and realize how dumb you looked.
- Owning a pet could turn into this trope in said pet's final years. The pain of watching a beloved dog or cat getting old, getting sick, and dying could make you wonder why you decided to get them in the first place considering the inevitable heartbreak experienced in the end.
- There are some who could argue this Trope explains every decision made in the entire length and breadth of HUMAN HISTORY.