What an Idiot!/Western Animation/Avatar: The Last Airbender

Book One
You'd expect: That Zhao would realize it's extremely unlikely that a newborn baby would have time to master one element let alone all four and would thus decide to kill Aang. Instead: Zhao decides to imprison Aang. You'd Expect: Zhao to realize that killing the moon is not only a mite bit overkill, but also would hurt the Fire Nation just as much as the rest of the world. So he'd think of some alternative that isn't nearly as stupid. Instead: Zhao kills the moon. Brilliant. And it's pretty clear that to him, the destruction of waterbending was a bonus. He just wanted to be able to brag that he killed the moon.
 * "The Blue Spirit": Zhao captures Aang who has less than a year to master all four elements if he is going to stop the villains' plan to take over the world. However, if Aang is killed he will simply reincarnate as a baby.
 * "Siege of the North": And of course, the defining idiocy of the series comes from Admiral Zhao during the first season finale. Zhao is invading the Northern Water Tribe in order to stop Aang from learning waterbending. Zhao is also aware that the Ocean and Moon spirits (the entities that power waterbending) are in the heart of the Tribe's city in the form of relatively harmless koi fish. Killing the Moon Spirit would destroy waterbending.

Book Two
You'd expect: The General would NOT try to piss off the AVATAR. Or to just realize that you CANNOT control a supernatural force if it requires a violent trigger. Instead: He has his men attack Aang in the climax of the episode, and when he finally does go into the Avatar State, the crazy bastard doesn't seem to mind that he and his men are getting their ASSES WHOOPED. Even when Aang's finally finished his mad rampage, he wonders out loud how to control him when he's in that state. Thank you for interfering, Sokka. The soldiers also back down as the Gaang refuses the armed escort. To Make Matters Worse: The armed escort would have been very handy to hold off the Fire Nation blockade, which forces the Gaang to trust singing nomads to get them through a shortcut via the Cave of Two Lovers, as well as for evacuating the Omashu citizens. Because welp, it turns out that Bumi surrendered the city to the Fire Nation despite his generals protesting, and the Gaang has to fake a plague to convince the new governor to free the citizens and undercover resistance. You'd expect: He'd demonstrate the good sense possessed by even the most scatterbrained Cub Scout and not touch the thing with a ten-foot-pole until he's 100% certain it's the right one. Instead: He drinks it and almost dies. The nurse that tends to him even lampshades this. You'd expect: After reading her the obligatory riot act for sneaking out at night, and probably a bonus one for associating with such "riff-raff" - he'd assign her a seeing-eye maidservant, fire the so-called instructor who was supposed to teach her only breathing exercises, and allow her to instruct the Avatar. Instead: He announces that he has been permitting her too much freedom by letting her wander the gardens of the family compound on her own, and that she will from now on be guarded 24/7, while ordering the Avatar and his companions to leave. When Toph bolts, he compounds matters by hiring the guy who kidnapped her, who was one of the earthbenders that she beat to bring her home by any means possible. You'd Expect: If Zuko really wants to take up chasing Aang again, he makes use of Aang's address on the flyer. Instead: He infiltrates the base of the local Secret Police, which is made up mostly of elite earthbenders, planning to steal a huge, flying furry monster which has horns, but no reason to be cooperative, what with having defended Aang against Zuko before. And Zuko has no idea whatsoever what he'd do if he actually got Appa out of there. To top it all off, he has no idea if the Dai Li actually have Appa - He goes there on a guess. You'd Expect: Iroh would take Zuko and give him a long talk to find out just whether or not Zuko is happy with their life, and if he is unhappy, how Zuko could possibly become happy, helping Zuko to divorce himself from his original obsession with trying to please his horrific father, Ozai and carve out a life for himself as per Iroh's lecture. Instead: Iroh takes it at face-value that Zuko, proud, honor-focused, dedicated, desperate to claim recognition for his own self, is happy being a faceless refugee in Ba Sing Se, lying about who he is. Zuko promptly betrays Iroh when Azula dangles a very real chance in front of Zuko that he can have everything that he believes he has ever wanted and still wanted; to go home and have things "go back to normal"... Being Fair: One of the most certain ways to get Zuko absolutely determined to do something is to try and pressure him not to do it, so Iroh has reason to believe taking the slow approach and letting Zuko convince himself will work better than lecturing him. He's also not at all expecting Azula to show up and actually offer Zuko a chance to sell out and get back home -- they are, after all, smack dab in the middle of the one fortress on the planet that the Fire Nation has never successfully conquered in decades of trying. You'd Expect: He would tell this to only those who absolutely need to know it when they absolutely need to know it. Only top commanders and soldiers involved in the operation, and those soldiers only on the eve of the invasion. The information is useless, after all, if anyone in the Fire Nation finds out, and all that would take is an unreliable lower ranked soldier to sell what he has learned. Instead: He tells it to three arriving Kyoshi Warriors... who he has never met before and who just happen to be Ozai's Angels in disguise, completely ruining the surprise attack before it even gets into the planning stages. There is no reason to give them this vital piece of intelligence and he only has Sokka's word that they're trustworthy (without Sokka getting the chance to confirm their identities) before he starts spouting off vital military intelligence to them. The Result: The Gaang only finds out too late, at the same time the Earth King does, that they're not the real Kyoshi Warriors when Ty Lee stupidly flirts with Sokka, and is confused when he points out he's dating Suki, the Kyoshi Warrior leader. Thanks to this moment of stupidity, the invasion fails in "The Day of the Black Sun" and many of the Gaang's allies end up in prison. To top it all off, comics like The Promise reveal that Kuei never forgave himself for trusting Long Feng or letting his city fall to the Fire Nation; he prepares to declare war again to protect his people when it seems that Zuko is backing out of an effort to return colonial cities.  You'd expect: For the King to tell Team Avatar that he mentioned the secret invasion plan to the fake Kyoshi Warriors. Or at least for the Team Avatar to, upon finding out about the deceit, asked whether the King told them anything important. Instead: the King doesn't say anything and Team Avatar never asks. It doesn't cross their mind, either, that the officials who knew about the plan might reveal it to the Fire Nation, under torture if nothing else. So the heroes go on with their plan with a ragtag army, only to be promptly defeated by the not-so-surprised Fire Nation. The only victory they get out of it is that Iroh also found out about the eclipse, staging a breakout after working out in prison for months; Zuko also takes the time to call out his father and defect.
 * "The Avatar State": While the Gaang is en route to Omashu so Bumi can teach Aang airbending, the adults escort them to a military outpost where an army will get them to the city. A general there, war-weary and a little traumatized from endless battles, convinces Aang to see if he can unleash the Avatar State willingly. While Katara knows it's a bad idea, the general shows Aang the sick bay, where injured earthbenders barely survived previous skirmishes. The Gaang does reluctantly admit that it's the Avatar's duty to prevent these wars from happening. Hilarity Ensues during a Failure Montage to force Aang into the Avatar State; caffeinated tea makes him hyper, surprising him does nothing, and making him one with the elements just coats him in mud. When Katara advises Aang to call it off, Aang tells the General that they should stop; he's only been able to access the Avatar Stare when he's in danger.
 * "The Cave of Two Lovers" While wandering the Earth Kingdom in the beginning of season 2 as fugitives from Azula, Iroh, the Eccentric Mentor of Avatar: The Last Airbender, comes across a plant that is either "the rare White Dragon Bush, whose leaves make a tea so delicious it's heartbreaking!", or else "the White Jade Bush, which is poisonous and covers the drinker with a suffocating rash."
 * "The Blind Bandit": Lao Bei Fong, a wealthy Earth Kingdom merchant, discovers that the blind 12-year old daughter he kept hidden within his estate has been sneaking out to participate in quasi-legal underground pitfights. He then witnesses firsthand how great of an Earthbender she really is when she beats half a dozen experienced adult earthbenders into submission and makes it look easy.
 * "Lake Laogai" Zuko does a few less than brilliant things, but consider the time he finds out that Aang in in Ba Sing Se, too, thanks to the "lost pet" flyer about Appa.
 * Iroh's whole plan of settling down as a refugee with Zuko in Ba Sing Se is pretty stupid, if you think about it, given Iroh knows very well that Zuko is a bundle of issues in a "Well Done, Son" Guy coating. For particular irony, Iroh gives Zuko a very intense spiel about how Zuko needs to think for himself and decide upon his own course in life shortly before Zuko does just that... by choosing to grab with both hands the slim hope Azula dangles before him that he really can come back to the Fire Nation and reclaim everything he's ever wanted.
 * "The Guru" and onward. The Earth King gets a major one. He has just received vital information that could turn the tide of the war against the Fire Nation, an eclipse that will happen in a few months and deprive firebenders of their power for long enough to defeat the Fire Lord. He pledges support and his army when the Gaang tells him that those seven minutes could end the war.
 * What happens next is even stupider, though, as shown in "The Crossroads of Destiny" and "The Awakening". The disguised enemies take over the city of Bao Sing Se, and the King is forced to flee. Team Avatar saves him, and he hangs with them for a while while Aang is comatose. The other Earth King officials who know about the eclipse plan are now prisoners of the Fire Nation.

Book Three
You'd expect: Roku to try and talk him out out it, to use the experience he gained in traveling the world for 12 years to explain why taking over the world is a bad idea, to take Sozin on a Diversity Tour of the world, to latch onto Sozin's arm and not let go until he is sure that one of the 5 most influential people in the world doesn't let go of his megalomaniac ideas. Instead: Roku blows Sozin off and tells him to just forget it. And when Sozin implores him to listen, Roku says that he doesn't want to hear anymore of this, leaving Sozin feeling betrayed by his best friend, bitter and isolated. This war really IS your fault, Roku.
 * "The Avatar and the Firelord": The newly minted Avatar Roku is celebrating his wedding, when he is approached by his best friend Fire Lord Sozin. Sozin tells Roku that it would be just swell to Take Over the World.

The Promise
You'd Expect: Roku to remember that Zuko is not Sozin. This is a scared, traumatized teenager trying to rapidly undo about three generations' worth of damage to the entire world. Instead: He advises Aang to stick to his promise, believing that it was his hesitation to hurt his best friend and brother-in-law, as season three revealed that led to Sozin starting his conquest. The Result: Thanks to the stress, Zuko nearly commits suicide a few times, and Aang in the Avatar State has to save him as Kuei prepares to march on the Yu Dao colony. Then Aang finds out that Zuko is Roku's great-great-grandson on his mother's side, and his fury knows no bounds. [[What the Hell, Hero?| He asks how the hell could Roku condemn his own family}} for something an ancestor did, and breaks ties with him briefly.
 * As the comic starts, Zuko extracts a promise from Aang to kill him if he ever becomes like Ozai. As a pacifist, Aang talks with Roku about this especially since Zuko is now his friend and overwhelmed with the responsibilities of being Fire Lord.