No, that's not a wig. That's their real hair. Hopefully, the realization that their hair is real will come with the first pull before they continue tugging to rip out strands of hair to intense discomfort.
Note that facial hair being mistaken for fakes can also apply.
This trope can be the subject of a quick gag, but it could be the plot of an entire story. One way to be Mistaken for an Imposter.
- Blake and Mortimer: The Voronov Plot has the English sneak Mortimer out of the USSR by having him travel with an ambassador and a bearded agent with the same build as Captain Blake. As they go through the airport, Olrik catches them and has them detained on grounds of leaving with an escaped fugitive (Blake), gloats about the laughable disguise (Blake's previous disguise was just a mustache), and attempts to pull off the agent's beard, promptly getting the agent to cry out in pain. Olrik's accusation falling flat, he's forced to let Mortimer go (Blake as actually disguised as the ambassador).
- The Life and Times of Scrooge McDuck: One chapter has the Beagle Boys disguise themselves as Santas to sneak into Scrooge's money bin. When they take off their disguises, Scrooge pulls at one's white beard... except it's the only one with a real beard, Pappy.
- In Tintin: The Blue Lotus, a man with a big bushy beard enters an opium den wearing dark glasses and a big hat. The villains recognize it's obviously Tintin wearing as many disguises as he can, tie him up, pull off his fake beard... and it turns out they've captured a diplomat with a real beard.
- In Tintin: The Broken Ear, Ramon and Alonso tried pulling the beard of an old man they assumed to be Tintin just to find out quickly that the beard was real. (Another one of their targets was wearing a wig but was also not Tintin.)
- In Tintin: King Ottokar's Sceptre, Tintin suspects that Professor Alembick has been replaced by an impostor, so he pretends to stumble and pulls on his beard. It turns out to be real and Alembick shouts, "Yeoww!".
Tintin: "It's real?! I mean, I'm really sorry."
- It later turns out that Professor Alembick is an imposter, but that the culprit is his twin brother.
- Total Drama: Unfinished Business: In order to keep Owen from eating all the food during the cooking challenge, Noah locks him in the fridge. Once he is finally let out, he is dressed in full tribal gear and has a grown a full beard. Noah asks what is with him and fake beards and drags Owen around by his actually very real beard.
- Ace Ventura: Ace attempts to tear off Einhorn's wig when he's trying to prove that she's actually Finkle in disguise. He's correct about her identity, but the hair is real.
- Austin Powers: Austin comes back from doing reconnaissance work when Basil Exposition introduces him to Basil's mother. Austin thinks she's a male spy in drag and punches her, knocking her to the floor. Austin goes to the mother and tries to rip her hair off, thinking it's a wig. Basil has to convince Austin that's really his mother.
- Played for Laughs in The Great Race. The Great Leslie is in a meeting with the board of directors of an automobile company to convince them to hold the title race. His nemesis Professor Fate is in disguise (wearing a fake beard) amongst them. When Fate speaks out against Leslie's plan, Leslie tries to rip off his beard and expose his fraud. When Leslie's attempt fails, Fate pulls on his own beard to demonstrate that it's real and accidentally pulls it off.
- The Mad Adventures of Rabbi Jacob: The cops pursuing Victor Pivert learn he's mugged a rabbi for a disguise, including the beard. They run into the titular rabbi Jacob thinking it's Pivert and try to yank his beard off, leading to them having to apologize. Unfortunately for him, Pivert has now been mistaken for Jacob himself and his family members think he's the imposter.
- In Miracle on 34th Street, Susan states that she does not believe Santa's beard is real, and he openly invites her to pull on it to prove that it is.
- In To Be or Not to Be, Jozef Tura, one of the protagonists, wears a fake beard when impersonating Professor Siletsky, a Nazi double-agent. After the real Siletsky's body is discovered by the Nazis, they place Tura in a room with the corpse to see what he will do. Tura proceeds to shave off the real Siletsky's beard and replace it with a spare fake beard, and then claims that the real Siletsky is the impostor, counting on his captors inevitably pulling on the corpse's beard. Tura then invites his embarrassed captors to pull on his beard, which they decline to do.
- Beastly: In an update of Beauty and the Beast, Kyle is a high schooler who has been turned into a humanoid animal covered in hair. He understandably becomes a recluse, but on Hallowe'en he takes the opportunity to go out, blending in with people in costumes and hoping to find a girl to break the curse. Unfortunately, the girl he tries this with is too interested in the quality of his "costume" and tries to pull some of it off with a very hard tug.
- Mr. Men: In "Little Miss Fabulous", Little Miss Splendid spreads a rumor that the eponymous Little Miss Fabulous is wearing a blonde wig. Little Miss Trouble tests this out by tugging on Little Miss Fabulous's hair (to the latter's chagrin), and finds out it's not fake.
- The Sherlock Holmes short story "The Red-Headed League" has a shopkeeper with red hair receive an invite to the League of Red-Headed Gentlemen. An interview is conducted with this man, which includes a pull on his hair, with the explanation that some candidates arrived wearing hairpieces, "and once, even paint." This turns out to be an invoked example, as the person who set up the League knows the shopkeeper personally and is well aware that his hair is real.
- A convoluted example in Discworld novel Moving Pictures. A group of wizards have stuck wires into their beards to make them look fake in order to go incognito, then have trouble convincing someone theyre really wizards once they need to again because he can see their false beards.
- Our Miss Brooks: In the episode "Mister Fargo Whiskers", Miss Brooks has reason to believe that teenage student Walter Denton will be impersonating a state school board official by the name of Fargo. Especially when it turns out that Mr. Fargo's first name is Walter! When Miss Brooks meets Fargo, she insulting mimics his twang (thinking it's a fake accent of Walter Denton). Then she tries to pull of Mr. Fargo's titular whiskers. Miss Brooks makes a hasty retreat when Walter Denton walks into the room . . . asking for help putting on his fake beard!
- Blackish: "Good Dre Hunting" has a recurring gag of Dre being convinced that Bow's therapist is wearing a wig. Even after the therapist pulls her hair in front of him to show it's not a wig, he's still not convinced. In the end, Bow also admits she thinks it's a wig.
- Horrible Histories: "Victorian Undercover Proprietor" (a parody of Undercover Boss) has Sir Titus Salt going undercover in one of his mills and discovering how horrible conditions are for his workers. At the end of the sketch, after he reveals himself, one of his workers says "I knew that were a disguise, as soon as I saw the daft fake beard." He yanks on it only to discover it is Sir Titus' real beard.
- Impractical Jokers: One of Murr's punishments had him trying to find someone wearing a toupee in a crowded restaurant. His method of doing this was tugging on people's hair, which led to immense discomfort to Murr and the other Jokers.
- Monk: Subverted in the episode "Mr. Monk Gets Fired". A wig is a crucial piece of evidence in a murder case, but its owner - the police commissioner - insists his hair is his own. This does appear to be the case at first, but then Sharona runs over and tackles him, pulling his hair as hard as she can until it pops off his skull.
- In a Christmas-themed episode of Mr. Bean, "Merry Christmas, Mr. Bean", Mr. Bean goes around pulling off the fake beards of several Mall Santas, but then tries to pull off the beard of one that has a real beard (who screams in pain, causing Mr. Bean to run away).
- New Girl, "Wig": In order to get Nick to loosen up around their beautiful temporary roommate Reagan, Schmidt and Cece make up a (fake) innocuous flaw: Reagan's hair is a wig. This appears to work until Nick tries to smell her hair.
- Sam & Cat: "#GettinWiggy" revolves around Cat telling Dice that competing hair model Jet is wearing a wig and them trying to expose him. Their attempt to blow Jet's wig off with a fan only endears his hairstyle to the photographer, and he is declared to be the choice for the magazine cover Dice was originally chosen for. Cat snaps and begins to rip off Jet's wig to expose him, only for it turn out to be his very real hair. Jet is taken to a scalp hospital in tears while Dice gets to be on the magazine cover, but Cat is arrested, who tries to defend herself by telling the police that Jet's hair does look a lot like a wig.
- That's So Raven: In "Mismatch Maker", Cory finds a lost dog and doesn't want to give it up to its owner. At one point, a kid named Chauncey, who looks nearly identical to Cory (and is also played by Kyle Massey), comes over to claim the dog, but Victor thinks it's Cory in disguise and tries to pull his "wig" off. And that's when the real Cory walks in...
Victor: I'm so sorry! I thought you were my son!Chauncey: Is this the way you treat your son?!
- 30 Rock: Tracy's wife, Angie, gets to be on a reality show centered around herself. However, her contract states she must rip out the weave of several people during the show, so she repeatedly tugs out Liz's hair despite the latter protesting it's not a weave.
- Will & Grace: In "The Old Man And The Sea", Jack tries to convince Will to join a swimming club. When Will expresses reluctance, Jack assumes it is because Will is wearing a hairpiece and tries to yank off his hair. Will then confesses he doesn't know how to swim.
- There's a character event in Monster Rancher Advance where Aroma tries to find out if Mr. Mardoc wears a toupee. Eventually, Mardoc allows her to try pulling on his hair to find out for herself... It's real alright.
- The Amazing World of Gumball: In "The Mystery", when trying to figure out who mauled Principal Brown and hid him inside Gumball's locker, one of Gumball's suspects is Rocky the janitor because of his bald spot on his hand. He claims that Rocky lost all his hair due to oldness (despite being only 25) and plucked off all of Principal Brown's hair due to jealousy, painted it orange and glued it to his body. Rocky defends himself by revealing that the bald spot on his hand is from accidentally spilling some kind of chemical substance that burnt his hair. Gumball still doesn't believe him until he tries (and fails) to pull it off.
- An episode of Dexter's Laboratory had Dexter try to prove Santa didn't exist and was actually his dad in disguise. He caught Santa in the act, accused him of being his dad, and even shaved his beard and hair, convinced that it would be his dad underneath. It wasn't.
- In The Flintstones episode "Moonlight and Maintenance", Fred goes to a wig store to purchase a disguise. The owner happily sells him a toupee from right off his head. Then at the last second, Fred decides to grab the matching mustache. The store man says
"The joke's on him, that mustache was real. EEYOWWW!"
- In the Rugrats episode, "Tricycle Thief", Susie's tricycle goes missing, and Susie doesn't believe Angelica when the latter says that she didn't take it. One of the lies that Susie reminds Angelica of is the time she told Phil and Lil that their father, Howard's hair was a wig. The twins recall how mad Howard was when they tried to pull it off, but how funny it was anyway.
- The Simpsons: In "Simpsoncalifragilisticexpiala(Annoyed Grunt)cious", Homer keeps mistaking the prospective nannies for men pulling a Mrs. Doubtfire, and attempts to remove their "wigs".
- SpongeBob SquarePants: In "No Weenies Allowed", one of the fish at Weenie Hut Junior suggests SpongeBob have a cool hairdo to get into the Salty Spitoon, so he runs off to a wig store. A familiar-looking sponge with a black pompadour arrives at the Salty Spitoon to introduce himself as a drifter who wants to enter the bar, and Reg tells him that he can see through the disguise and pulls on his hair. SpongeBob then arrives with a rainbow clown wig, and Reg tries unsuccessfully to fix the drifter's hair before apologizing and letting him inside.
- Total Drama: During the episode "Camp Castaways", Owen (after realizing he's alone for eleven minutes) grows a full beard. Both Heather and Gwen both try to pull it off, thinking it's fake. Owen wails in agony both times.