Coincidental Accidental Disguise

The main characters are all sitting in the dark, watching a horror movie about a yellow monster with scales and a tail. One character decides to go get some chips and dip, but while looking for the dip in the fridge, WHOOPS, he drops the bottle of mustard, steps on it, and gets covered in mustard. Then he tries to wipe it off, but he slips and falls, and the paper towels stick to his back. Then he tries to open the chips, but the bag explodes, flinging chips everywhere. The chips, of course, land on him in such a way that it looks like he has scales.

He walks back into the room and the other characters scream! He, coincidentally, looks like the monster from the film! Hilarity Ensues.

In general, it is easy to wander into something that makes you look like a monster. Getting covered in flour or having a bedsheet fall on you makes you look like a ghost, having a stuffed head fall on your head makes you into a beast, etc.

Compare Easy Impersonation.

Anime & Manga

 * Happens to Kaitou Kid in Detective Conan OVA 10. He loses just enough pieces of his costume that the Detective Boys mistake him for Shinichi his Expy.

Comic Books

 * When Scamp gets chased off for jumping in someone's yard, Tramp decides to go after him into the "Haunted" house. Having discovered that the shoe he's hidden in has holes in the bottom, Scamp decides to continue his jumping practice from inside the shoe, which gives Tramp the impression that the boot is moving due to a ghost. Eventually, Scamp jumps his boot into some white wash, which gives Tramp a second fright when Scamp comes home entirely white.
 * One comic from the anthology It Was a Dark and Silly Night (written by Lemony Snicket and drawn by Richard Sala) involves a girl spotting a somewhat intelligent, largely laconic yeti outside her window. She goes out to investigate, and meets another girl, who gives her some marshmallows. As she searches, she becomes covered with so much snow that she begins to resemble a yeti herself, and is mistaken for one when she approaches a house, especially since the sticky marshmallows made it hard for her to talk.

Fan Fiction

 * "Zecora's Gift", a My Little Pony Friendship Is Magic fan-comic, has Derpy do this in the classic "horror movie startle" way.

Film

 * A character in Rat Race accidentally disguises himself as Hitler (with a mustache-like smudge on his face being the least ridiculous aspect) and ends up on the stage of a World War Two veterans meeting.
 * He's also driving a VW Sedan (Hitler's real car, in fact) and due to very precise burns on his tongue and hand he was also talking German-sounding gibberish and showing his middle finger.
 * Naturally, said character was actually Jewish (Jon Lovitz, to be precise).
 * A not-so-accidental version occurs in The Emperors New Groove, where Pacha's wife and kids set Yzma up to look like a piñata.
 * In It's a Very Merry Muppet Christmas Movie, Fozzie, while carrying a bag of money to the bank, accidentally gets painted green and is mistaken for The Grinch.
 * In the opening scene of Hot Shots a pilot miraculously survives the mid-air destruction of his fighter, only to be shot by hunters as he now bears an uncanny resemblance to a moose, thanks to some sticks that have become stuck on his helmet.
 * In a Scary Movie spoof-scene of 8 Mile, the Eminem-type character pulls on a white hoodie which makes him look like a member of the Ku Klux Klan, and then absentmindedly greets the crowd by thrusting out his arm at a 45-degree angle. A jump cut shows him getting tossed out a window.
 * The Nazis actually despised the Ku Klux Klan, but who cares?
 * In Mean Girls, Cady walks in on Janice and Damien while wearing her Halloween costume, and this trope happens. She's supposed to be dressed up as--in her words--an 'ex-wife', but Janice and Damien were currently watching a horror movie and lightning and thunder just happened to crash as Cady walked in.
 * In Snow White and The Seven Dwarfs, the dwarfs run out of their home when they think there's a monster inside (it's really Snow White). Dopey, lagging behind as usual, falls in a pile of pots and pans and runs out with the pots tangled up over his person. The others think he's the monster and attack him.
 * In Schtonk!, the satire about the faked Hitler diaries, the counterfeiter is sitting at his work while wearing an old Wehrmacht coat. He has a fever, and his sweaty hair sticks to his forehead. Then he spills some ink, cleans it up with his handkerchief, sneezes, cleans his nose and unwillingly leaves a spot looking like a Hitler moustache. And then, his partner in crime comes in and tells him that people want proof that the diaries were written by noone but Hitler himself. Cue the counterfeiter looking into a mirror.
 * In Wayne's World 2, Wayne roes in some friends to spy on his girlfriend meeting with a sleazeball suitor. From a telephone pole Wayne, dressed as a construction worker, sees them through binoculars. He radios Garth, dressed as a traffic cop, who in turn radios their accomplices, dressed as a sailor at a USO event and a leather-wearing biker working on his chopper. When Wayne's girlfriend notices, they abort and run into a random doorway, which takes them into a gay club, and onto the stage, where the DJ sees them and mistakes them for Village People impersonators, putting on "YMCA". Then, the Indian from Wayne's dreams shows up...
 * Pretty much the plot of the Laurel and Hardy short "The Live Ghost" - shanghaied onto a ship's crew, they think they accidentally killed a fellow crewman, who is merely drunk, and falls into a trough of whitewash. You can see where this is going.
 * In Eurotrip: The main character is in the Vatican, and he sneaks about in a private room of the Pope that leads to his balcony. There he quarrels with his friend, who puts a pope hat on his head. He slips and grabs the curtain of the balcony door, and it falls down with him. When he gets up, he accidentally opens the door and the curtain wrapped all around him looks like a pope's robe and the curtain rail in his hands like a pope's staff. With him looking like this, the huge crowd on Saint Peter's Square thinks he is the new Pope.
 * It goes even deeper than that. Prior to that, the bell signalling the death of the Pope is rung by one of the protagonists who "wonders what this rope is for" and one of the pope hats catches on fire and is thrown into the fireplace, releasing the white smoke that signals a new Pope has been selected. The crowd is waiting for his appearance when Scotty appears on the balcony.
 * In The Muppet Movie, Dr. Teeth and the Electric Mayhem paint Fozzie and Kermit's car to keep them safe from Doc Hopper. When Doc Hopper manages to recognize them anyway, Kermit spots a billboard that just happens to match the paint job, and has Fozzie pull up in front of it so they can hide.
 * Mystery Team combines this with Paper-Thin Disguise. Troy's disguise gets him into a building because the costume is so obvious the guard assumes he's there for the costume party.

Literature

 * In the Doctor Who Expanded Universe short story "The Andrew Invasion", the titular Andrew is mistaken for the Doctor on three occasions (admittedly by some very stupid aliens): Once on his way back from playing in a cricket match (Fifth Doctor costume); once on the way back from his cousin's wedding, where he was an usher, and the colour scheme was green and gold (Eighth Doctor costume); and once in tartan pyjamas with a cat motif, and with a red and yellow patchwork quilt around his shoulders (Sixth Doctor costume).

Live Action TV
"Mr. Pitt: We WILL annex Poland by the Spring, at any cost! AND... our stock will rise HIGH! *raises hand*"
 * Also happened in Ned's Declassified School Survival Guide. Ned looked like Wild Boy, the subject of a famous painting.
 * That's So Raven: while sneaking into the shoot of a zombie movie Raven fell on the catering table, getting covered in food, causing her to blend in perfectly with the zombies.
 * Black Books established that Manny had a loose tooth, and a massaging device could put your back out. Also, he begins limping when the events of the episode activate a stress cramp in his leg. Putting these together had Bernard becoming a ranting Mad Scientist with Manny as Igor.
 * Black Books also did this for the first time Bernard meets Manny - he wakes up to see him hovering overhead dressed in a white hospital robe with his long hair loose, surrounded by white light...
 * Scrubs used this trope in an episode where JD was helping the Janitor "move house", and was told upon the task nearing completion to put on gloves and a hat to protect from fibreglass and dust in the attic (or something like that), followed by the Janitor leaving, and the house's real owners showing up to JD dressed like a burglar.
 * Not actually coincidental or accidental. The Janitor is a Magnificent Bastard.
 * Highly provocative example from Seinfeld: a series of comic mishaps involving being dressed in his riding clothes, accidentally spilling ink on himself (and scratching under his nose), and so on leave Elaine's boss looking just like Hitler. Just before he goes into a meeting to discuss the "invasion" (merger) of Poland Springs.


 * Similarly, in Father Ted, Ted finds himself standing in the exact position required to make a square bit of a dirt on the window look like a Hitler moustache, to the consternation of the Chinese family who were invited over specifically to prove that Ted wasn't racist.
 * Another Seinfeld episode culminates in Kramer carrying a cane, wearing Joseph's Amazing Technicolor Dreamcoat, donning a woman's hat, and to complete the effect, having an altercation with a woman on the street, leading to his being mistaken for a Pimp.
 * In one episode of the Dick Van Dyke Show, Laura and Rob dye something black, only to find that the black dye won't come off their hands and arms... on the night Rob speaks at an NAACP dinner.
 * Not entirely coincidental, but in the Amazing Stories episode "Mummy Daddy", an actor shooting a mummy movie in a hick town, dressed head-to-toe as a mummy, hears his wife is giving birth and rushes to the hospital without changing out of costume. According to town legend, a mummy came to life fifty years ago and wreaked havoc. Hilarity ensues.
 * Truth in Television. It happened with Boris Karloff when he was filming Bride of Frankenstein. And since Karloff also played The Mummy in the classic Universal movie...
 * One Arrested Development episode has a bunch of kids telling ghost stories/urban legends and one is telling a version of The Hook. Then, at the right/wrong moment, Buster stumbles out of the bushes, and when the kids see his Hook Hand, they run away in terror.
 * The dressed-as Hitler-variation happened in one episode of Childrens Hospital. Of course, Judaism was a recurring theme in the episode and the character involved was the Jewish doctor (the guy playing him isn't Jewish though).
 * In the 30Rock episode "The Tuxedo Begins", Liz decides to act crazy so people will give her space on the subway. She starts with a tangled white wig and smeared lipstick, and adds heavy eyeshadow, a green sweater-vest, a pink gym bag, checkered socks and a worn purple overcoat.

Music

 * A rather dark and non-comedic version of this trope is the song "Iron Man" by Black Sabbath. In the song, a man travels to the future and sees that the apocalypse was brought about by a man made of iron. He goes back in time to warn the people in his modern time of the situation, but encounters a magnetic field that turns his body to steel and renders him mute. When the people in the present mock him for his appearance, he becomes angry and tries to get revenge on humanity, creating the future that he attempted to stop.

Newspaper Comics

 * Used in a 1950s Peanuts strip where Lucy is inflating a paddling pool (so has goggles and flippers on and is using an airpump) only for it to blow away and land on Charlie Brown, who's reading a scare story about the then-contemporary UFO craze. Charlie Brown misinterprets the paddling pool as a UFO, Lucy as a Martian and the airpump as her Death Ray.

Theater

 * A Running Gag in Arsenic and Old Lace is that homicidal gangster Jonathan Brewster has been made to resemble Boris Karloff by his plastic surgeon, who was inspired by a horror movie (and very drunk at the time). No doubt it was even funnier during the original run, when Karloff himself played the part.

Video Games

 * In The Curse of Monkey Island, Guybrush is mistaken for a giant chicken demon ("El Pollo Diablo") after being tarred and feathered. He can then choose to either unknowingly wonder what's going on or play along with a local chicken restaurant owner, who has a bit of a grudge against El Pollo Diablo to boot.
 * You have the option of English or Spanish for this. Yes, even being confused and unaware of what's going on.
 * In the first Space Quest game, setting up this kind of situation is required in order to progress. Roger Wilco needs to hide in a washer/dryer, get caught in the cycle, and emerges in one of the evil alien uniforms.

Webcomics

 * This Xkcd strip.
 * Alt Text implies that this is not the first instance of such a Coincidental Accidental Disguise.
 * Done with a healthy dose of Mood Whiplash in College Roomies from Hell when Dave ends up with a rotten pumpkin crammed down over his head and Margaret shoots him, taking him for a pumpkin-headed zombie monster.
 * In Freefall, Florence the Antropomorphic Wolf seeks shelter from a storm and medical attention... just as the house owner is watching a werewolf marathon. Crouched (to keep a wound closed), showing teeth (trying for a smile) and backlit by lightning, Florence is not a reassuring sight.
 * In Sluggy Freelance, the very-short Broadman sneaks into a party disguised as a chef, while still wearing fake Pointy Ears from his Vampire: The Masquerade LARP, the end result being that Torg and Riff mistake him for the cookie-elf they're looking for.
 * There was also the second Halloween arc, where Riff's redesigning the fog machine to run on Rogaine caused him and Torg to sprout hair all over their bodies, just in time for the first of the many annual demons from the Dimension of Pain to show up and ask the 'werewolves' how to find Torg.
 * Dangerously Chloe had a girl from Teddy's school having a date with him out of curiosity - after she witnessed a succubus impersonating him reverting to the quite obviously female body shape, noticed another succubus, who didn't morph her horns away in time and thought that Teddy and his associates are shapeshifting aliens... made her shriek.

Western Animation

 * In an episode of Foster's Home for Imaginary Friends, Bloo is mistaken for a ghost out of a horror movie after he catches a nasty cold, prompting him to turn pale, emit moaning noises and spit up "ectoplasm". Ew.
 * Happened also in Camp Lazlo, where Raj was covered in marshmallows and looked like a yeti.
 * And to Scoutmaster Lumpus when he got covered in leaves and had a couple of eggs wedged down his throat to turn him into the mythical snipe.
 * In an episode of The Simpsons, Homer managed to get his head stuck in a beehive, then coat the beehive in blueberries, and then roll around, tangling himself up in the green picnic blanket. When he stood up, he looked like he was impersonating Marge. (He even lost his voice from yelling, so all he could make were scratchy noises like Marge makes.)
 * Another example from The Simpsons would be the Horrible Camping Trip episode where Homer ends up in his underwear, covered in mud and mistaken for Bigfoot.
 * Also, Homer ends up covered in green paint, and goes wild with rage, in front of special guest Stan Lee. ("I Am Furious, Yellow.")
 * "He's not the Hulk! I'm the Hulk! RAAAGHHH..! ...I don't understand, I did it once before!" "Oh, please, you couldn't turn into Bill Bixby."
 * Also, while Grampa was competing (and failing) in a race, Groundskeeper Willie was cutting the grass with a scythe. It started raining, so Willie decided to put on his black raincoat, Grampa meanwhile was getting tired and his dentures fell out. Willie tried to return the dentures to him while in the raincoat and still carrying the scythe, leading Grampa to mistake him for the Grim Reaper, so he started running faster and won the race.
 * Due to the side-effects of the treatments needed to keep him alive, Mr. Burns was once mistaken for a glowing alien.
 * Also happens to Marge in one episode, in which a series of mishaps leave her looking like a stereotypical witch.
 * In Catscratch, a type of this happens, where Gordon has a violent allergic reaction to broccoli (that he doesn't notice), which coincidentally makes him look exactly like the monster from a movie his brothers were watching. Later, Gordon has a different reaction to chocolate, which makes him looks like another monster from a comic book his brothers were reading.
 * During the Total Drama Island episode "Phobia Factor" Cody's garbage bomb explodes, covering him in sludge and trash, as he staggers back towards camp, holding his arms out zombishly and making unintelligible groaning noises (from disgust) he comes across a terrified and lonely Bridgette who immediately screams and makes a run for it.
 * Cartoons often have a character being wrapped in toilet paper and looking like a mummy, such as Timmy Turner in "Scary Godparents" and Candace Flynn in "Are You My Mummy?"
 * Every Looney Tunes short featuring Pepe LePew involved Penelope the cat accidentally getting a white stripe on her back somehow.
 * Notable exception: 1959's "Really Scent" starts with the cat (Fabrette) born with a stripe. Heckuva birthmark.
 * Carried over to Tiny Toon Adventures with Fifi leFume, with the accidental disguise usually befalling Furball The Cat or Calamity coyote.
 * And in at least one short, Penelope wound up with a case of the sniffles impeding her sense of smell, and Pepe got black paint down his back, obscuring his stripe.
 * An episode of Goof Troop has Max and PJ being reminded of a horror movie killer by Pete (intentionally) and Goofy (by accident). And in the final scene of the episode, Pete is scared to death and faints by the appearance of a masked chainsaw-weilding man... which turns out to be Goofy, cutting off a tree.
 * There's also the episode where Goofy decided to become a street mime, although this one was less accidental. Trying to come up with a costume for his performance, Goofy finally decides to wrap himself head to toe in aluminum foil and pretend to be a "robot" mime. Unfortunately, Max and P. J. have also decided to wrap themselves in foil to pretend to be space aliens as part of a prank; they broadcast a fake alien transmission over every television set in Spoonerville, with Max announcing: "Our mission? Quite simple: to take over Earth!" Cue immediate citywide paranoia, and some pedestrians in front of an electronics store (with many TV sets in the front window) happening to glance down the street and spot Goofy going into his mime act. Hilarity Ensues.
 * The Penguins of Madagascar, "I Was a Penguin Zombie": Skipper escapes from the vet after breaking his wing, and through a combination of green topical ointment (which numbs his mouth, making him unable to speak), tangled gauze, talcum powder, and a sprained ankle, ends up looking and acting like the living dead.
 * Can anyone even count the number of times this happened to Shaggy (or Scooby) on Scooby Doo?
 * Spongebob in SpongeBob SquarePants has done this multiple times. While he and Patrick were warning the citizens of Bikini Bottom about a "flying monster coming to eat you," Spongebob flew over the city after being blown up like a balloon. In another episode, he's at a sleepover with Pearl and her friends watching a zombie movie when he gets rootbeer for everyone by absorbing it, and becomes a lookalike to the movie zombies.
 * There was also the episode, Krab Borg, where Spongebob mistook Mr. Krabs for a robot. At first, Squidward didn't believe his ramblings, but after seeing Mr. Krabs with piercing red eyes (due to getting salt in his eyes), a pair of tongs in his claw (mistaken for metal pinchers) and two batteries in his back pocket (from his radio that broke and the batteries were in his pocket cause he planned to give them to Pearl for Christmas), he starts to believe Spongebob.
 * Another example is Squidward the Unfriendly Ghost. Spongebob and Patrick accidentally melt a model of Squidward that they mistook for the real one, and while they were panicking about saving it, the REAL Squidward comes out of his bathroom, covered in white powder from fixing himself up, and naturally, Bob and Pat freak out and vow to do anything for Squid's "ghost" in apology. Eventually turns into Stop Helping Me! on his part, especially by the time they try to bury his "ghost".
 * In the Adventures in Care-a-Lot episode "King of the Gobblebugs," Oopsy makes up a story about seeing the eponymous creature, getting the others all riled up to catch it. Later, Oopsy ends up falling into a barrel of glue and gets all manner of things stuck to himself, making the others think he's the king gobblebug, and they capture him.
 * In the Chuck Jones cartoon The Bear That Wasn't, a bear ends up on a construction site with a cigarette in its mouth and holding a cup of coffee. No one can see through the Paper-Thin Disguise and they insist he's "a silly man who needs a shave and wears a fur coat" no matter how much the bear protests.
 * One Flapjack episode has the titular character, after a series of unlikely events, being mistaken for a Genie in a Bottle.
 * In one Maryoku Yummy episode, Ooka makes up a story about the Yorglesclubber that ends up scaring not only the wishes, but herself and Fij Fij. Maryoku goes out to prove that there's no such thing, but along the way she gets covered in mud and various plants, so that when she comes back, the others think she's the Yorglesclubber and attempt to trap her.
 * On Drawn Together, through a series of coincidences (illness, pranks, the job wheel), Wooldoor ends up looking like a very stereotypical Hasidic Jew. This is Drawn Together of course, so Hilarity Ensues.

Real Life

 * Truth in Television: A large man reported taking a trip to China while bright red all over from a sunburn, which would have made him resemble the Buddhist lord of the underworld and judge of souls, Yama in Chinese and Enma in Japanese. He scared small children.
 * Ken Kirzinger (the actor who played Jason Voorhees in Freddy vs. Jason) needed dental work while he was filming the movie. He went to the dentist in full Jason costume and makeup as it would be too hard to take it all off, scaring the crap outta all the doctors and nurses.
 * There's also an anecdote about Kane Hodder (Kirzinger's predecessor as Jason) once running into a few hikers in the woods; shortly after filming finished for the day, so he was still dressed as Jason. The next day, he had to answer a few questions for police.
 * Christopher Lee alarmed an elderly Italian couple when he knocked on their door in the middle of the night, covered in blood from a car accident. They'd been watching him play Dracula not long before.
 * During the 30s and 40s The Three Stooges made several films mocking Nazi Germany, during which Moe capitalized on his resemblance to Adolf Hitler by dressing up as the dictator and playing him as a power-hungry buffoon. One morning they shot some footage on the birthday of Moe's daughter. As soon as the shoot was over he ran out the door without taking off his costume so that he could make it to her party in time. The police received several calls from concerned citizens who claimed to have seen Adolf Hitler running several red lights.
 * This news item:
 * On Halloween day (1989), Tallahassee, Fla., K-Mart employee Jeff Sablom was taking a break in the back of the store to try on the Batman costume he had planned to wear to a party that night when a security guard asked for his help to apprehend a shoplifter. Said the guard later, "You should have seen that man's eyes when he looked back and saw Batman chasing him." Sablom recovered four cartons of cigarettes and two videocassettes. [Gainesville Sun, 11-2-1989]
 * Definitely a Crowning Moment of Awesome.