Your Door Was Open

"Jane, we've talked about this! You can't keep walking into our flat uninvited -- this is not an American sitcom!"

- Steve, Coupling, a British sitcom

Not to be confused with There Was a Door.

A common situation in a TV show with limited time to show events, where a character will suddenly appear in another character's home with no explanation. It can be interpreted as merely a shorthand to indicate that the character has in fact knocked and been let in but the scene is too boring to air. However, the trope often appears in contexts where that should not be possible, like when the person entering the house walks in on someone's private affairs, or is a villain, or is out of favor with the resident and walks in just to berate him, etc. Why nobody ever, at the very least, locks their door when they want to be alone is a great mystery. One with no answer whatsoever.

The Drop-In Character does this all the time.

Compare with Swiss Cheese Security.

Anime and Manga

 * Happens all the time in Kannagi. The protagonist stopped locking his door after Nagi got to live with him (instead of, you know, giving her spare keys), and didn't lock the door when they both were inside as well. If people are ringing the bell at all, it is just that they are polite.
 * Mahou Sensei Negima: Negi wanders into Chisame's apartment while she's dressed as her alter-ego "Chiu-chan".
 * Pokémon had an episode where Professor Oak suddenly appears in the "new character of the week"'s house to provide plot-important information; no one bats an eye.
 * As I recall, it wasn't the character's house, it was their family business - a greenhouse. Oak being a Pokémon researcher certainly didn't hurt.
 * Door locks are nonexistent in To LOVE-Ru. None. Zilch. Nada. Not on bedroom doors, not on the school roof, and definitely not on the washrooms, which results in many Accidental Pervert situations in the name of Fan Service and Rito getting the crap kicked out of him by pissed-off girls.
 * In Fairy Tail, every guild member walks into Lucy's home as if they owned it, especially when she's sleeping or taking a shower/bath, sometimes together with her. Hilarity Ensues because Lucy is not amused.

Comic Books

 * Subverted by Rorschach in Watchmen as it is obvious that he broke the door and then waited for the owner to come home. Rorschach then criticizes the owner for installing such a cheap, flimsy Gordian Knot-brand lock.

Fan Works

 * In one My-HiME Shizuru/Natsuki fan comic, Shizuru lets herself into Natsuki's unlocked room while she's asleep, and Natsuki finds her sitting across her table from her when she wakes up. Shizuru chides her for leaving her door unlocked, apparently from being tired from all the make-up work she's been doing, and Natsuki promises to be more careful in the future, but notes that no one out there is more "dangerous" than Shizuru.
 * The Katawa Shoujo fic From Shizune's Perspective has an example in which the intruder is also the one who forgot to lock her door. Shizune walks into her own unlocked room to find Misha and Hisao.

Film
"Janey: How'd you get in here? The door was bolted Jake: There's a giant hole in the side of your house."
 * Parodied in Not Another Teen Movie:

Literature
"Ponyboy: *Wakes up, walks downstairs and sees Tim Shepard on the couch reading a newspaper. He obviously came in while everyone was asleep.* ...Hi, Tim. Tim: *Without looking up.* Hi. Ponyboy: Can I..get you some breakfast? Tim: Nope. *Folds up newspaper and walks out of house.*"
 * The Outsiders: Ponyboy explains that he and his brothers always leave their door open since you never know when a friend might need a place to crash, and they are rarely surprised to wake up and find some random gang member sleeping on their couch, or even a rival gang leader reading a newspaper while sitting in their chair, having already made breakfast.


 * Little Women: Aunt March frequently barges in, complaining about how her family doesn't lock their door.

Live-Action TV
"Jackson: Jack? O'Neill: He's a barber. Jackson: Broke into your house? O'Neill: Yeah... Jackson: Second week in a row. O'Neill: Mm-hmm. Jackson: Alarm. O'Neill: I'm thinking "dog". Joe Spencer: You could try locking your front door."
 * In Babylon 5, Londo returned to his quarters to see that his door was open. G'Kar was waiting inside, wanting to purchase a certain plant for a religious ceremony.
 * Virtually any American Sitcom, particularly noticeable in Friends. This tendency is Lampshaded in Coupling season 4.
 * It was lampshaded a few times in Friends too: when Monica and Chandler agree to move in together, Monica tells him to lock the door to her apartment, then unlock it again for the first time as her roommate. Chandler replies: "The door hasn't been locked in five years, but sure." Then in the final episode, Monica and Chandler leave their keys on the counter as they leave the apartment... and then so do all the others.
 * Kramer from Seinfeld and Charley from Empty Nest were both based almost entirely off of this trope—both neighbors to the main characters, both enter without knocking in a distinctive manner, and both steal food from the main character's fridge.
 * The show To Catch a Thief has two ex-cons who, with the owner's permission, and while videotaped, try to steal (then later return) things from the owner's house. They often gain access through unlocked doors. Then they help the owners improve their home security and try again some time later.
 * Parodied in Birds of a Feather, where Dorien had a habit of just walking into her neighbors' house. At one point, they locked the door. She smashed the glass panel next to the lock, undid it, and came in anyway.
 * Buffy the Vampire Slayer. Becomes a Running Gag in Season 4 when different characters keep wandering into Giles' home, with him lampshading by saying "I thought I locked that door." or "Now, I know I locked the door that time!"
 * This was a Running Gag on Even Stevens with the character Beans. Lampshaded in The Movie when the family is sitting down to dinner and Beans pops up, prompting Donny to say "This kid is starting to freak me out" and another character to propose changing the locks. Possibly averted by the fact that everyone found Beans weird and unsettling.
 * Seinfeld - in many episodes George and Elaine enter Seinfeld's apartment without him first buzzing them in through the intercom. Kramer's appearances are easily explained, since he and Jerry have swapped apartment keys.
 * In one episode, though, Kramer's trademark entrances were subverted when a paranoid Jerry locks his door for once. Instead of Kramer bursting through the door like usual, the rest of the cast just hears a loud bang against it.
 * Smallville - this happens so often that characters Lampshade it. Particularly nonsensical for Lex Luthor, who has cameras and security systems. This is a Justified Trope when Clark is involved, but not when it's, for example, Jimmy Olsen.
 * From Stargate SG-1:


 * Steve Urkel on Family Matters treated the Winslow house as his own. When asked at one point why he never knocks, he said that if he did, no one would let him in.
 * NCIS, any character that wants to speak to Gibbs when he's at home can, due to the fact that he never locks his door.
 * Done frequently on The Secret Life of the American Teenager. A notable example happened in the season one episode, "Maybe Baby" when nearly every regular character ended up in Amy's house, arriving in groups of two or three, just to tell her they would support her if she wanted to keep her baby. They have gotten better about it in later seasons (meaning it's more common to see people actually knock on the door and wait for someone to answer it) but it's not completely absent.

Newspaper Comics

 * A New Yorker cartoon from 2002 has two agents walk into someone's house saying "We're from Homeland Security. You left your door unlocked."

Video Games

 * Though most RPGs use this, Golden Sun gets a special note for actually having bandits lampshade this and take advantage of a town's lack of home security to loot from the mayor, several homes, one of the protagonists and a holy sanctum.

Web Comics
"Strong Bad: Is there like a sign on my door that says, "Wanted: Everyone I hate. Inquire within"? King of Town: [randomly walking in] I didn't see one."
 * Homestar Runner: The title character finds his way into Strong Bad's house on many, many occasions. Even though Strong Bad is outspoken in his hatred of him. At one point Homestar lampshaded it by questioning whether he actually lived in Strong Bad's house.


 * Minions At Work: Unlocked at any rate.

Western Animation
"Dr. Weird: (Standing in front of a gaping hole in the wall) "Who could have penetrated my impenetrable fortress?""
 * In an episode of Aqua Teen Hunger Force, when Dr. Weird's latest invention is stolen away through the hole caused by his previous invention.

"Pooh: How did you get past my Hunny-napper traps? Rabbit: Your back door was open. Pooh: Oh!"
 * Done in Winnie the Pooh. The titular Pooh has set up an elaborate, if hasty furniture barricade in front of his Front door and is patrolling it with a popgun rifle. He hears a knock and is nervously trying to ascertain the identities of his friends knocking at the door, when Tigger bounces the bear, with Rabbit and Piglet walking in behind.

"Ben: How'd you get in here? Kevin: The usual way. By the way, you might wanna fix that hole I punched in your door. Ben: You could have knocked! Kevin: I sorta did."
 * "Your back door was open" is used several times in the animated movies & episodes.
 * Lampshaded in Ben 10: Alien Force once when Kevin just shows up in Ben's room.

Real Life

 * A while back, Twin Cities police officers had a campaign where they'd go up to houses during the night, and leave warnings if they door was unlocked. Eventually, this lead to a pair of officers not-quite-legally entering a house and waking up a homeowner to politely tell him that he is an idiot for not locking his doors, leaving his garage open, and leaving the keys in his ignition.
 * Michael Moore also did this in Bowling for Columbine, in Toronto, just to show off the difference between how Americans and Canadians behave in regards to home security.