So, finally we have arrived to the climactic moment in the story: the main character is fighting the villain, the Love Interest is struggling to free herself from chains, and our hero's friends are coming to his aid... And then comes the Wham Shot. Both the "villain" and the Love Interest smile and cheer the protagonist, then a whole bunch of friends and seemingly "unrelated" characters enter and join them. Congratulations, the whole plot was an elaborate set-up, and everyone (except the protagonist) was in on it.
There may be varying reasons for this: sometimes it's done just for fun and teasing (for example, as a convoluted April Fool's joke or a pretext to a Surprise Party), or it may be the Love Interest's way of flirting with the main character. At other times, there are more serious purposes (like helping the protagonist deal with psychological issues or teaching him a lesson if he's giving himself airs); however, this doesn't prevent everyone else from having fun while doing it. In some instances, it can also overlap with Secret Test.
When a plot becomes overly complex and mind-bending for the media's format, for instance, when you have Conspiracy Kitchen Sink, supernatural events, and life-altering revelations in a comedy show episode, expect this trope to come into play soon.
In order to qualify for this trope, the staging has to be benign and created by the protagonist's true friends and loved ones. When a hero does this to trick the villain or vice versa, it instead qualifies as Massive Multiplayer Scam or some sort of Gambit.
Subtrope of The Ending Changes Everything; its own subtropes include April Fools' Plot, Surprise Party, and Scary Surprise Party; Sister Trope to and often overlaps with False Crucible, and may also overlap with Not-So-Forgotten Birthday and Mockspiracy.
This is usually an Ending Trope, so THERE WILL BE SPOILERS.
- The "Conan Edogawa Kidnapping Case" episode of Detective Conan has Fumiyo Edogawa, a woman claiming to be Conan's mother (Conan cannot have a mother, since this is a fake identity) and attempting to kidnap him. However, she is eventually revealed as his real mother Yukiko. Being a loving mother but at the same time a very childlike person, as well as a top-class actress, Yukiko is almost a living embodiment of this trope: she adopts numerous aliases and hides her true identity from Conan in a number of other episodes, even when there's no real need in this.
- Haruhi Suzumiya: The murder mystery from the "Remote Island Syndrome" episode was merely a plot by Itsuki meant to entertain Haruhi.
- A number of stories from the Scooby-Doo, Where Are You? series by DC Comics have the team actually stage a mystery in order to play a joke on one particular gang member.
- In the Chupacabra-Cadabra story from the Scooby-Doo DC Comics series, the gang arrives to a magic show in Mexico for Shaggy's birthday. A monster called Chupacabra appears, and the team members start disappearing one by one... eventually, it is revealed that it was all a pretext for Shaggy's surprise birthday party, and everyone, except Shaggy and Scooby, was in on it.
- Likewise, in The Secret of Hotel Hush, the supernatural mystery turns out to be a pretext for Scooby's birthday party - this time, Shaggy was also in on it.
- In Ghost in the Machina, Fred, Velma, and Daphne staged a monster mystery at Big Ralph's Car Wash as a way to get Scooby and Shaggy to take a bath.
- In Clueless, the gang staged a fake kidnapping of Velma as a prelude to her surprise birthday party.
- Zig-Zagged in The Game. Nicholas agrees in participate in what is advertised as this from the very beginning, but then it seems that the people who are staging it are really up to no good. Then it turns out that it was a game after all, but Nicholas mucked it up and killed his own brother (who was in on it) in the process. Finally, it is revealed that even his brother's death was staged.
- April Fools' Day is all about this. An April Fool's party turns into a string of violent, slasher-style murders, but then it turns out that all the murders were staged as a part of an April Fool's prank.
- The plot of Pants on Fire is that the main character Jack's lies are all coming true, like the time he fought off lumberjacks (an excuse for breaking his arm) or got abducted by aliens (he was late for an appointment with his friend). In the end, it turned out that his sister Hannah staged everything, from a nonexistent kid named Mikey that Jack claimed to tutor (as well as his dog with a robotic tail), to Jack's wrestler uncle, to his girlfriend Lisa from Arizona who drove to Jack's neighborhood, to the aforementioned lumberjacks and aliens, all as a ploy to get Jack to quit lying.
- In Anger Management, it seems like Dave's psychiatrist, who was assigned to help him with anger management, is mentally unstable himself, and is psychologically abusing him (including attempting to steal his girlfriend). It turns out that everything was a part of Dave's treatment, and a number of other characters (including the girlfriend) were involved in it.
- The whole plot of Jules Verne's "Tribulations of a Chinaman in China" was staged by the protagonist's mentor, philosopher Wang, to teach him the value of life.
- In Alice, Girl from the Future, Alice's grandmother Lucretia, who is a sorceress (formally a stage magician) and The Trickster, is really fond of such antics. Once, when Alice and her friends tried to get rid of her by telling her a made-up story about nonexistent creatures, she pretended to believe them and scared them with holographic images of these creatures.
- In Castle, the "Lives of Others" episode involves Castle staying at home because of a trauma and getting involved into a Rear Window-style murder mystery when he sees something suspicious in an apartment across the street. Eventually he gets Beckett to believe him, she goes to the apartment and is threatened by the killer, Castle breaks into the apartment with the police... and there's a birthday party behind the door. Everything was staged by Beckett as a birthday present for Castle.
- In All The Small Things, Esther and Michael see peculiar lights coming from inside the church as they drive past on their way home one night. They stop to investigate, wondering if it's being burgled, when suddenly the lights all come on, revealing that it's a surprise party to celebrate their wedding anniversary. Esther was in on it.
- Cheers did this twice in one season:
- First, the Halloween Episode continue their Prank War with Gary's Old Town Tavern. However, it appears that their prank (a hologram of Carla's head) has caused Gary to have a fatal heart attack. Sam refuses to believe that Gary is dead all throughout the memorial service and funeral. Finally, he comes to realize that they've just killed Gary by accident. Then it's revealed that the whole thing was an elaborate prank directed at Sam. Carla then claims the entire city of Boston was in on it.
- Later, it's discovered that Gary's has just been bought out by a new company and the Cheers gang decides to restart their Prank War with the new owners. The new owners retaliate violently and it's discovered they're actually a Mafia family. The cops show up to take them into protective custody. Woody, Carla, Norm, and Cliff accept, but Sam decides not to join them. They're taken to the middle of nowhere and left alone with a pay phone. Sam then calls them on the pay phone and reveals that the whole thing was his way of retaliating for the aforementioned Halloween prank.
- On Just Shoot Me!, a prank Maya pulls on Elliot seems to go horribly awry, which turns out to be one massive prank on her orchestrated by Dennis.
- One Night Court Halloween episode has Dan casually "selling his soul" to a man claiming to be the devil, but then getting more and more frantic when the guy starts displaying encyclopedic knowledge of Dan's past misdeeds. It turns out that it's all a prank on Mac's part and Dan faints in relief.
- Monk: in Happy Birthday, Mr. Monk episode, Monk is constantly suspecting that Natalie is preparing a Surprise Party for his birthday. In spite of that, she (together with Stottlemeyer) does manage to outsmart him by preparing a black Cadillac that's supposedly trying to kill them... but is in fact a pretext for the surprise party.
- Several examples appear on M*A*S*H.
- Playing elaborate practical jokes proves to be one of BJ's favorite hobbies. In one episode, he makes a bet with Hawkeye that he (BJ) can prank Hawkeye, and then proceeds to do nothing and lets Hawkeye destroy himself with paranoia.
- Col. Potter even did it once, setting up a joke against his entire staff with the help of a visiting officer friend who fakes a rage-induced heart attack.
- The comedy ending of the white chamber invokes this.
- The April Fool's episode of As Told by Ginger has Ginger sending a fake love letter to Dodie from Dustin, the weirdest guy in school - a joke gone terribly wrong when Dodie responds favorably, and Dustin does not. In the end, it is revealed that the joke was actually on Ginger - Dustin was in on it, along with Dodie and Macey.
- The "Family Feud" episode of Hurricanes involves this: when Helmut and Yorg start a feud, the whole team, including Amanda, stages a fake kidnapping of Yorg so that Helmut could realize how much does he actually care for him and come to his rescue.
- Some episodes of Magic School Bus have Mrs. Frizzle play jokes on kids and deliberately mislead them, so that they would learn some new things on their own.
- In Going Batty, it is strongly implied that she intentionally played up the "vampire" image (took the children's parents to a castle, gave them tomato juice that looks very much like blood and made it appear as if they had turned into bats) to lure the kids on another trip and make them learn more about bats.
- In Cold Feet, this was partly unintentional: she wanted to tell the class what really happened to Liz, but seeing their reactions, she decided it would be better if she played along and let them learn on their own.
- The SpongeBob SquarePants episode "Fools in April", SpongeBob annoys Squidward with his April Fool's pranks, only for Squidward to pull a harmful prank on him that nobody finds funny. When he's called out on it, Squidward tries to (tries to) apologize to SpongeBob. When he finally does, it turns out that it was all a giant prank by SpongeBob, and the entire town was in on it.
- Adventure Time: In "Mystery Train", Finn attempts to solve a murder on a train, only for the entire thing to prove to be an elaborate game staged by Jake as a birthday treat for him.
- The My Little Pony: Friendship Is Magic episode "The Mysterious Mare Do Well", the mysterious rival who'd been dogging and showing up Rainbow Dash all episode turns out to be... all of her friends, who'd been trying to snap her out of her Acquired Situational Narcissism.
- Taken Up to Eleven in the "Deadomutt" episode of Harvey Birdman, Attorney at Law: Harvey is falsely accused of murder, sentenced to death and spends 5 years in jail... and all of this is just pretext to a surprise birthday party.