Sometimes a character is confused about another character's sex. It could be because they're a crossdresser, they're trans, they have an Ambiguous Gender, or maybe they're a Bifauxnen, Dude Looks Like a Lady, or Lady Looks Like a Dude. The normal reaction would be to simply ask but some characters opt for a different, more aggressive way.
An Outfit Rip Sex Check is when a character is made to reveal their sex in a decidedly non-consensual matter such as ripping off their clothing or receiving Clothing Damage. It's often a bullying tactic if the characters are young enough but is typically listed under Sexual Harassment and Rape Tropes, though it can be Played for Laughs.
This should go without saying, but Do Not Try This at Home; if the description didn't make it clear enough, this is considered a form of sexual assault in the real world.
Compare Crotch-Glance Sex Check.
- In Adolescence of Utena Saionji mistakes Utena for a boy until partway during a duel he cuts her shirt open.
- After School Nightmare's protagonist is an intersex teen. Mashiro, along with other troubled teenagers at his school, must enter a Dream Land to deal with their deepest problem before graduating. Early in the dream world a character dressed as a Black Knight is curious whether Masahiro is a crossdresser or a girl so he rips open Masahiro's shirt and skirt with his sword. In the real world Masahiro instantly wakes up and tries to see who the person is but isn't allowed by the nurse, though he learns soon later.
- The one-shot Cotton Candy Love has elementary aged bullies trying to check under the skirt of their classmate, who recently began going to school as a girl.
- Attempted in Ikki Tousen when Kyocho Chuuko's judo classmates refuse to believe that she's a girl and rip her clothes in the dojo to "clear the doubts". Then Sousou steps into that, thinks that they're trying to gang-rape her, and his Superpowered Evil Side kicks in for the first time. There are no survivors except for the two of them.
- Ryoma, one of the one-shot protagonists in IS: Otoko demo Onna demo Nai Sei is intersex. She was raised as a boy but always considered herself a girl. In elementary, due to not acting masculine enough, she was bullied. Male classmates once tried to get her to take off her underwear so they could see if she was really a boy but she beat them up. The bullying ended and she started acting more masculine. However, at age 17 female puberty hits and causes an emotional issue between her living as male but having a feminine body.
- Invoked in the one-shot Kanojo ni Naritai!? The protagonist tears open his own shirt to reveal to his crush that he is really a boy. He originally began crossdressing because he thought she was a Butch Lesbian but it turns out she's not.
- In Love Stage!!, Shougo rips open Izumi's dress to show Sena that Izumi is actually a guy.
- In the yaoi one-shot Nise x Koi Boyfriend, two guys try to get Satoi to have sex with them. It isn't shown what happened but somehow he ended up with his shirt ripped open. They were grossed out at Satoi being a crossdresser and wanted to humiliate him by taking pictures of him nude and putting them online, but Satoi's boyfriend came to his rescue.
- Ranma ½:
- Ukyō often dresses like a boy. At several times, other characters suddenly exposes her (Sarashi-clad) breasts to prove her gender to new people. She never takes it well.
- Ranma once got stuck in girl form and had to fight Mousse that way. To keep his Gender Bender a secret from Mousse, he pretends to use magic to make himself look like a girl during their fight but Mousse is angered by what he perceives to be an attempt to humiliate him and systematically rips off Ranma's clothes until she's completely naked in front of a watching audience. In a subversion, despite Ranma's exposed body clearly being that of a girl’s, Mousse and the audience still assume that he’s a boy and is just using incredibly convincing-looking magic.
- Tooru from Tokyo Ghoul Re is a transgender man. This is revealed by a Ghoul attacking him in the back of a cab. The Ghoul only eats women with scars and is confused by Tooru's sex so he rips open his shirt, revealing his chest binder and the fact he's Covered with Scars. He beats up Tooru and tries to take him as his next victim, but Tooru is rescued.
- UQ Holder!: Unconvinced that Kuroumaru is a guy, Touta pulls down Kuroumaru's pants while the latter is knocked out from Yukihime's attack in chapter 4. Kuroumaru wakes up to punch him before he can check anything, though.
- In an elementary chapter of Wandering Son, while at a public bath, some boys try to see whether Nitori, who is a closeted transgender girl, is a boy or a girl. She ends up screaming loudly which scares them off and causes them to mock her feminine "gay voice".
- An accidental one in Yuuna and the Haunted Hot Springs. Oboro is very androgynous-looking. Kogarashi assumes Oboro is a guy until he rips Oboro's clothes during their fight, revealing her breasts. This works to Oboro's advantage because Kogarashi doesn't fight women.
- In Seven Soldiers, Shining Knight's sex is revealed after Galahad rips off part of her shirt, revealing her bound breasts to Gloriana.
- Dark Secrets: As a kid, a boy pulled down Cassidy's pants after hearing rumors that she's transgender.
- Implied in Disney's Mulan. Mulan decides to fight in the Chinese army against the Huns in place of her father, who is too old to stand a chance in battle. She does this by cutting her hair and dressing up as a man, since women are not allowed to enlist in the Chinese military. After a battle with the Huns in which she saves the lives of her fellow soldiers, she gets injured and is taken to a medical tent. The doctors, while treating her, find out she is a woman and relay this news to Captain Li Shang and the rest of the army. Li Shang is ordered to execute Mulan, since death is the punishment for impersonating a soldier, but spares her life as she had saved his.
- Ace does this at the end of Ace Ventura: Pet Detective to reveal the bad guy.
- Twice in Austin Powers: International Man of Mystery:
- Early in the film, Powers grabs a pretty mod girl and declares "it's a man, man!" and pulls "her" wig off, revealing a male spy.
- Later in the film, Powers meets Basil Exposition's mother and thinks she's another male spy in a little old lady disguise, but it turns out this one really is a little old lady.
- In Boys Don't Cry, when trans man Brandon's friends become suspicious about his sex, they corner him and yank down his pants and underwear to reveal that he has female anatomy.
- The protagonist of Tomboy spent the film presenting as a boy to the other kids. When her mother finds out she reveals Laure's a girl to a boy she got into a fight with, which causes him to tell everyone else. The other kids make a girl who likes Laure pull down her pants and confirm if she's female or not.
- White Chicks: When rival FBI agents Gomez and Harper arrest Brittany and Tiffany Wilson who they believe to be protagonists Kevin and Marcus Copeland in disguise, they try to "prove it" by forcibly taking off their clothing in front of the staff... only for it to turn out that they captured the real Wilson sisters, who punch them unconscious in retaliation for the undressing.
- Inverted in Monstrous Regiment: The squad, entirely composed of girls pretending to be boys to enlist disguise themselves as washerwomen to infiltrate the captured fortress. They are caught, and the guards laugh at yet another attempt at crossdressing to get inside. They start wailing about this unfair treatment, until Shufti lifts up her skirt, showing a distinct lack of "socks". Polly turns her best contemptuous glare towards the captain, asking in icicle-covered tones if perhaps he needs to see the rest of the squad naked as well. The captain, utterly defeated and knowing he's going to be known as a loathsome pervert who gets off on stripping women, leaves quickly and the girls are allowed to continue unhindered.
- Mushoku Tensei: Jobless Reincarnation: Rudeus accidentally does this to Sylphy. He had mistaken her for a girly-looking boy because of her short hair. One day, he insists on taking a bath together and when Sylphy refuses, he forcefully takes her clothes off. He then takes a look at Sylphy's crotch and realizes his friend is a girl, leaving Sylphy in tears.
- Alanna's true sex is revealed to the public in the second Song of the Lioness book during her duel with Duke Roger when he accidentally cuts through the special corset that she uses to flatten her chest, causing her to inadvertently flash the entire crowd.
- The Commish: Tony approaches the senior mother of a wanted bank robber who he suspects of harboring her son and/or the money he had stolen. Tony tells her and her friend, another little old lady, that unless she tells him where the money is he'll get a warrant to tear her house apart looking for it. He also mentions that her son had stolen $200,000. The woman is outraged, because apparently her son had told her he stole less than that and was holding out on her. Her friend assures her that her son wouldn't do something like that but the mother knocks her wig off, revealing that she is really the son, in hiding. Tony then reveals that the son had only stolen $80,000.
- Farscape. In "Coup by Clam", the crew stop on a planet where women are oppressed. A mechanic comes up to modify Moya, only to be exposed as a Sweet Polly Oliver when Chiana uses the "rip open jacket to reveal breasts" version. Though it's a Captain Obvious Reveal seeing as the mechanic isn't very butch.
- Invoked in Game of Thrones. During her journey to Winterfell after her father's death, a disguised Arya struggles to look like a boy while travelling with future members of the Night's Watch. As her friend Gendry immediately notices she's not a boy, he tells her to show "his" peepee and piss in front of him as proof. She gives up and reveals her true name shortly after.
- Art of Fighting:
- If you beat King with a super attack, "his" clothes will rip, revealing King as a woman all along.
- In the second game, the same thing will also happen to Yuri. They retain this in The King of Fighters 94, 95, and XIII.
- Final Fantasy V: Early in the game, after having to swim through a sunken ship's hold, Bartz and Galuf strip down to dry their clothes over a fire, and force Faris do do the same, only to discover, true to this trope, that Faris is cross-dressing woman.
- In Power Instinct: Matsuri Senzo Kuyou, after [Bifauxnen Hikaru Jomon]]get beaten with a Special KO, her clothes are ripped and it's revealed her breasts are covered by a Sarashi, revealing Hikaru is a girl instead of a boy as she wanted to be seen.
- Knights Errant: In the original version, Oswald is revealed to be assigned female at birth when the prince cuts off his shirt. The prince already knew, though, and was only proving it to make a point.
- Happened on Venus Envy to the transgender Zoe twice:
- Nuke accidentally finds out when trying to kill her, under Grace's orders, but after Larson punches him in the face and knocks him out, he tells Grace he has no memory of the incident.
- Nina finds out similarly, trying to stab her in a fit of jealousy.
- Used in a comedic fashion in Star vs. the Forces of Evil when Marco (pictured) pretends to be a princess. He gets outed as a boy when his dress top is pulled down exposing his one chest hair. The crowd is actually willing to believe he is girl despite this (especially when some of them are very hairy non-humans), but Marco is ready to drop the ruse by that point anyway.