A Shaggy Dog Story is a plot with a high level of build-up and complicating action, only to be resolved with an anti-climax or ironic reversal, usually one that makes the entire story meaningless. The term comes from a type of joke (called "gildersome" in The Meaning of Liff) that worked the same way — a basic premise, a long amount of buildup, and a deliberately underwhelming punchline.
The classic example is a man who bankrupts himself trying to return a shaggy dog to a rich family in England for reward money — when he finally makes it there, he's told that the dog "wasn't that shaggy" before the door's slammed in his face. The End.
For television, these stories tend to be found in two varieties: serious and comedic.
Serious shaggy dog stories generally put the protagonist on a quest or goal, only to undermine the purpose at the last minute. For instance, a cop spends all episode trying to convict a criminal, only to watch the perp be hit by a car and die before he's brought to justice; or a doctor searches all episode for the cure to a mysterious illness, which seems to miraculously cure itself. This plot highlights the futility of characters' jobs, or the cruel ironies of life. An even crueler variant is Shoot the Shaggy Dog.
Comedic shaggy dog stories are often parodies, undercutting typical plot structures by offering a ridiculous coincidence or unforeseen twist, or even just making the entire episode irrelevant. The Simpsons enjoys these. Comedic shaggy dog stories can be frustrating in their randomness, but often succeed in execution.
See also Gainax Ending. Can compare to All Just a Dream and Overly-Long Gag, and overlap with Happy Ending Override. A reveal that It Was with You All Along may feel like this to the protagonist. For short stories which build up to an unbelievably wretched pun, see Feghoot. Contrast with Shaggy Frog Story, where a familiar story is mangled for comedic purposes. Can also lead to a "What Now?" Ending, should the protagonist himself realizes that his adventure is all for nothing.
When this is the result of Bad Writing, it may be a Writer Cop Out.
Not to be confused with Scooby-Doo, which is a cartoon featuring Shaggy's dog. Also not to be confused with Disney's The Shaggy Dog.
Spoilers Ahoy! Since this trope is about stories' endings, spoilers are inherent and will be unmarked.
Meta example in Yu-Gi-Oh!. Oftentimes, players will try building the best decks in the current metagame (which tend really put a drain on the wallet even when its a budget deck) only for the forbidden/limited lists to hit said decks and either ban or restrict the key cards. This makes the high-priced cards became much more affordable and makes the deck easier to make...but can no longer be used to its fullest potential (or even outright) anymore, leading to wasted effort on the part of the players. The cycle continues into the next metagame and the next and the next and the next and so on so forth.
Norm MacDonald every time he's interviewed so the guy says to me he says to me the guy says...
The spoken-word piece "Moose Turd Pie", the most famous version being done by folksinger/historian Bruce "Utah" Phillips. A guy joins a work-crew of some sort (logging, railroading, etc) where the person that complains the most about the food is forced to become the Camp Cook. He gets assigned this duty, and decides to get out of it by making the eponymous dish. He serves it up for dessert, the biggest, meanest guy on the crew takes a single bite, throws down his fork, and loudly declares: "That's moose turd pie!!" ...and hastily adds "It's good, though!"
When the extended flashback in the strip Nine Chickweed Lane began, it was promoted as being the story of how Gran fell in love with her husband; it finished as being how marrying O'Malley was a consolation prize because her true love and Juliette's birth father had to return to Austria.
The Luann story with her latest Love Interest Quill seems to be ending up as one of these. After constant Will They or Won't They?, they finally decide to get romantic... and just then his phone rings with news that he has to move back to Australia. He leaves to pack, and decides not to even see her again to say goodbye. Averted as Luann and Quill continue their relationship online. Quill even visits again in June 2013.
...and he moves back even later in 2013. As of now, it seems the story isn't over yet.
There was a very long series of Peanuts strips involving Peppermint Patty training for an ice skating tournament that ran over a whole winter. First, she hired Snoopy as a coach. Then she convinced Marcie to make her a skating dress; Marcie tried her best, but she couldn't sew, and made an awful dress. It almost ruined their friendship, until Marcie's mother made Patty a beautiful dress. Then Patty needed to get a new hairdo to go with it; Marcie was no good at that, so Patty went to Charlie Brown's dad - who's a barber. Unfortunately, he mistook her for a boy, and gave her a boy's haircut. Patty averted another disaster by buying a wig... But in the end, it all turned out to be pointless, because the tournament was actually a roller skating competition.
In a bizarre invocation of the Fleeting Demographic Rule, WCW's Halloween Havoc 2000 pay-per-view featured a Sting vs. Jeff Jarrett match, with Jarrett dressed up in Sting face paint. Throughout the match, several fake versions of Sting interfered in the match (reminiscent of 1990's Halloween Havoc, when Sid Vicious fought Sting and was later attacked by a fake), and the real Sting easily handled all of them. One would expect there to be a big payoff from all the fake Sting madness, but the match ended with Jarrett whacking the real Sting with his guitar to win the match.
WWE one - John Cena made a shocking comeback to win the 2008 Royal Rumble just four months after an injury that was said to put him down for at least seven months to a year. He invoked his title match against Randy Orton (who was awarded the WWE Championship upon Cena's injury) at No Way Out instead of WrestleMania... and then won by DQ, which meant he didn't get the title. Then he got another two title shots, and lost both of them before moving into another feud without ever getting any revenge on Orton.
The 1/21/13 episode of RAW held a "Beat the Clock Challenge," the winner of which would choose their own entry number in the upcoming Royal Rumble match. The winner was Dolph Ziggler, however when he goes to turn in his victory and choose his place as the last guy to enter, Vickie Guerrero informs him that he would only have his choice of entering the Rumble first or second, which function exactly the same except for how it goes into the record books. So it turns out that after three matches to determine the winner, the winner's prize is literally being given the worst possible entry in the Rumble. Vickie Guerrero hated Dolph Ziggler for dumping her the month before, which is probably why she did that to begin with.
The rules of the Royal Rumble state that a competitor is eliminated when both feet hit the floor. In 2012 Kofi Kingston walked on his hands to the steel steps and was able to reenter the match. In 2013 he leapt onto the back of another competitor and ended up on the announcers' table. He struggled to think how to get back to the ring and finally figured he could use a rolling chair. Only this time, Cody Rhodes eliminated him before he could get back in.
Gyorgy Ligeti's opera Le Grand Macabre: Death (called Necrotzar) announces the end of the world. People prepare for the final moment. At the end: nothing happens, except Death dies. Cue Epileptic Tree justifications.
The Story Guy videos from LoadingReadyRun are based almost entirely around this trope. Installments such as Gilled Cheese and Rare Book have the Story Guy go on at great length for what is eventually revealed to be no point at all.
This story is the best and most perfect incarnation of this trope. Be warned, it's a very long read.
In Survival of the Fittest, this occurs more often than not, due to the brutal nature of the game. Entire arcs can be left either unresolved or rendered entirely meaningless when someone integral simply dies.
This is more or less Simon Wood's entire arc is one of these. Poor guy couldn't even pull a Heroic Sacrifice off right.
Alex Rasputin; killed two people in v4, and was on the path to redemption. Suddenly, Liz Polanski destroys a camera, and Danya blows his collar.
In his review of Taylor Swift's Fifteen, Todd in the Shadows tells the story of a heart wrenching break up from his past. He then destroys the mood of the story by revealing that it never happened to him but was instead the plot of an episode of Saved by the Bell.
Chapter 2 of "Axe Cop" (the Moon Brothers arc) is this. The Moon Brothers find their family turned into bats, travels to Earth to defeat the villain who did it, meets up with Axe Cop's party, gains a bunch of utterly random power-ups, defeat the villain... and finally realize that they had a magic potion all along that could have turned their family back into humans, making the entire story-arc mostly pointless.
This commercial for Bridgestone tires. It even has dogs. The ad starts with a dog finding its lover having sex with another dog. The dog is so shocked it starts running away and arrives at a road with lots of cars passing. The dog jumps in front of a car, which stops almost instantly thanks to its Bridgestone brand tires. The end.
The Great White Sheet Game: Typically played at co-ed college parties with some amount of alcohol, often on road trips where the participants have multiple hotel rooms. One person who has never played before is chosen as the Player, while all those who have played before take on the roles of "Master" (for the leader of the game) and "Others". The Player sits on a bed, and has a sheet tented over him. The Master then explains that this is a test, and that the Player must follow the instructions that the Master or the Others give, to the letter. The game then proceeds, first with the Master describing a scene: "You are walking through the desert. It is hot, and you are thirsty. You realize you don't need to be wearing as much as you are. Take something off, and pass it to me." Usually, the Player removes something inconsequential—jewelry or shoes. The Others then continue in the same vein—embellishing and otherwise confounding the statement, but always with the admonition to remove something the Player is wearing needlessly. As time goes on, articles of clothing start coming off and getting passed out. The game ends when the Player figures out he's supposed to take off the damn sheet. If he's already naked underneath, well, then the Master and Others won the game.
Boy Scouts of America has a version where a number of newer scouts stands before a crowd and all place blindfolds on themselves. They are ordered not to make a sound for the duration of the game and are told to take an article of clothing off. The ones who take the blindfold off are quietly told to remain silent and the game is ended when the boys all have their blindfolds off or there are any boys reduced to their undergarments.
There are cards in Munchkin that can make a battle this: say you've encountered a Plutonium Dragon and its Evil Twin, facing painful death should you fail to beat them or run away. After numerous bonuses and anti-bonuses have been played on the monsters, the dragon's Baby Clone, and its Mommy, have been introduced to the fight, multiple one-shot items have been used to help or hinder you, several different methods of backstabbing have been employed, lengthy negotiations of teaming up have been had, and you're ready to reap your whopping eight levels and twenty-five treasures... Some asshat plays a few cards, making the dragon and its twin, clone, and the clone's mommy already dead (and dead broke), or something to the effect, leaving you without any levels or treasure, and everyone many cards poorer. Which is, of course, very munchkinly indeed, and highly recommendable in the spirit of the game.
This GIF is an extremely abridged version of the Lord of the Rings movies, except the characters forgot the Ring at home and find out only at the end.