History Main / SelfOffense

* In one of the non-fiction books by Michael Veitch in which he interviews Australian WW2 flyers, he interviewed a turret gunner who barely avoided shooting a menacing plane that loomed out of the dark, only for it to turn out to be another Lancaster bomber. When he reported this to his commander however, the latter was furious that he hadn't fired the moment he saw a threat, regardless of who it turned out to be.

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* Non-humorous example: In ''Film/TheDeparted'', [[spoiler: Matt Damon's character stabs some random restaurant worker in the chest, believing him to be Leonardo Di Caprio's character.]]

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* A RunningGag in ''{{VideoGame/Xenogears}}'' involves [[TheLancer Bart]] repeatedly mistaking [[TheHero Fei]] for an enemy, to the point where he [[spoiler: shoots down a massive airship that Fei and the rest of the Kislev party [[GrandTheftPrototype are currently hijacking]]]], without checking to see if it was friendly first.

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* In ''FruitsBasket'', Tohru is walking home from work when she hears someone is following her. Remembering there were rumors of a pervert hanging around she bashes the person in the head with her school bag. Turns out it was just Kyo who came to meet her.

* In one episode of ''ScoobyDoo'', Daphne mistakenly clobbered Shaggy with a vase in this context.

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* In ''FruitsBasket'', Tohru is walking home from work when she hears someone is following her. Remembering there were rumors of a pervert hanging around she bashes the person in the head with her school bag. Turns out it was just Kyo who came to meet her.

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* This can happen to Batman in [[VideoGame/BatmanArkhamCity Arkham City]] while in the Joker's warehouse. One of the medics is hiding from thugs and when she hears Batman approach she jumps out from behind some boxes and takes a swing at his head with a 2x4. Being Batman, you can [[MadeOfIron stand there and take it with no ill effects whatsoever]].

* ''TheTwilightZone'' episode "The Monsters are Due on Maple Street".

* Non-humorous example: The death of Polonius in ''{{Hamlet}}''.

* When pigs launch HostileShowTakeover of ''TheMuppetShow'', Kermit and Fozzie are locked into the boiler. Fozzie decides to club the pig guard to escape, but when the door opens its actually Gonzo, the latest hostage who gets conked!

* In an episode of ''HogansHeroes'', after a lady prisoner nearly brains Hogan with her high heel:

* Parodied in ''FamilyGuy''. When the house is broken into, Peter arms himself with a baseball bat and goes to investigate. He comes across Meg in the hall and stares at her while she asks several questions about what is going on. He then whacks her and says, unconvincingly "Sorry, Meg, you startled me." She was not amused.

* In the first ''ScaryMovie'', a young woman beats a group of trick-or-treaters senseless in this context.
* Used to gruesome effect in the horror movie ''TheStrangers'': the two main characters, terrorized in their home by masked invaders, are hiding behind a makeshift barricade in a back room with a shotgun, waiting in terror for their pursuer to appear in the doorway... and when someone finally does, the male protagonist shoots immediately, blowing the head off of-- his best friend Mike who has come to pick them up.

* Done in ''AbbottAndCostello Join The Foreign Legion''.
* Non-humorous example: In ''TheDeparted'', [[spoiler: Matt Damon's character stabs some random restaurant worker in the chest, believing him to be Leonardo Di Caprio's character.]]
* Played hilariously straight in ''AFishCalledWanda'' by Kevin Kline's character to John Cleese's.

* Another Non-humorous example pretty much sets up the entire plot of ''Film/{{Blade}} 3''.

** In a likely homage, Sam Raimi used this gag in both ''[[Franchise/EvilDead Evil Dead 2]]'' and the prototype short film ''Within the Woods''.

* In ''JohnnyEnglish'', Johnny performs this, then pins it all on a mysterious "aggressor".

* Also done in ''TheGreatRace''.

* A RunningGag in ''{{VideoGame/Xenogears}}'' involves [[TheLancer Bart]] repeatedly mistaking [[TheHero Fei]] for an enemy, to the point of him shooting down a massive airship that Fei and company [[GrandTheftPrototype happened to be hijacking]], without checking to see if it was friendly first.

** Repeated in the prequel, Arkham Origins, this time with a corrupt Warden.

* In ''JohnnyEnglish'', the titular bumbling secret agent performs this, then pins it all on a mysterious "aggressor".

A character sees or hears that someone is coming. Thinking that it's a bad guy, he prepares a mallet, a baseball bat, a net, etc. When the person appears, he strikes... and then notices that it was his friend rather than a bad guy.

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* In an episode of ''WesternAnimation/{{Thundercats}}'', Mumm-Ra tricks Lion-O into attacking Tygra with the Sword of Omens this way. Because the Sword can only be used for good, it breaks, forcing Lion-O to risk his neck finding someone who can repair it.

Compare FriendOrFoe. Sister trope of CatScare where approaching danger turns out to be a harmless critter. See also DontSneakUpOnMeLikeThat.

* ''Series/DoctorWho'': In "The Romans", Barbara hits Ian over the head with an urn will trying to attack the intruders in the villa.

* In ''JonahHex'', Jonah was leading the Confederate soldiers who opened fire on Stonewall Jackson (see RealLife examples below).

* Parodied in ''FamilyGuy''. When the house is broken into, Peter arms himself with a baseball bat and goes to investigate. He comes across Meg in the hall and stares at her while she tries to ask what is going on. He then whacks her and says, unconvincingly "Sorry, Meg, you startled me." She was not amused.