In most sitcoms there is always the one character who is responsible and trustworthy. They are structured, neat and orderly and would never think of doing anything reckless or illegal. They might be a Control Freak but they don't have to be.
If this character exists in the series then 9 times out of 10 there's going to be an episode where one of the other characters tells them they need to "lighten up" or "cut loose". Our responsible character will start to worry that they are too boring and so will eventually get wild and spontaneous.
It's almost a given that they will go overboard and something akin to We Want Our Jerk Back happens where the rest of the characters realise they do need some order and discipline in their lives, which the responsible one provided. They'll be back to being responsible by the end of the episode and they'll either reveal how much they hated being spontaneous or resolve to be a bit more fun without going overboard.
If it's the latter then expect this to be forgotten by the next episode. This will almost always happen to a female character but male examples aren't unheard of as well.
- Used as a bit of a joke in the film of Harry Potter and the Order of the Phoenix, where Hermione remarks that it's fun breaking the rules. It's worth noting that in the book, it is Hermione's idea to start up an illegal Defence Against the Dark Arts society which could technically count as an example of the trope.
- Terry Pratchett's Discworld novel Making Money has an example that gives a Shout-Out to the Twelfth Night example below: the austere and humorless bank clerk Mavolio Bent, a man who ran away from the circus to join a bank, suddenly re-asserts his destiny and heritage as a circus clown.
- In the Labyrinths of Echo novella A Trip to Kettari, the resident Stoic Shurf consumes an otherworldly drug (specifically, marijuana) and gambles away all the funds he and Max were given for the mission in a single night. He deeply regrets the incident for years to come.
- In a two-part episode of WKRP in Cincinnati Disc Jockey Dr. Johnny Fever falls into an alter-ego (Rip Tide) a shallow host of a Disco-themed t.v. show. This provides him with more fame and a larger fanbase but it also causes him to give into his urge to exploit his fame to satisfy his basest desires.
- In the Season two Episode A Many Splendored Thing of the show Homicide: Life on the Street uptight detective Tim Bayliss investigates a murder that involved participants of an SM sex club. The end of the episode finds him (having been given a kinky-looking jacket as a gift) strolling along Baltimore's infamous sex strip "The Block".
- Monica in Friends got two examples of this.
- One was a minor subplot where the other friends suggest she not get so uptight about things like coasters and leaving her shoes out of her room. The end of that episode has a moment where she can't sleep because she's worrying about leaving the aforementioned shoes. She gets to considering putting them in her closet and getting up early to put them back out before she realises "you need help" and goes to sleep.
- Another episode had someone stealing her credit card. When Monica tracked the woman down, she found said woman a lot of fun and started doing everything with her to the point where she was drunk in the middle of the day and kept missing work.
- One episode of Full House has Super OCD Danny caving in to his family and friends' requests to loosen up and becomes "Dirty Dan".
- In What I Like About You Jeff says to Val he wishes she was more spontaneous. She goes a bit wild during the episode but reveals at the end the whole experience "nearly killed me".
- In Sabrina the Teenage Witch Zelda temporarily moves in with Sabrina and her college roommates and decides to become a "hang-loose gal" which involves eating the entire contents of the fridge, spending all night at a rave, driving around in a van with a guy named Vick and trying to get a tattoo. In this case it's resolved by Zelda's subconscious stopping her from doing something untrue to herself.
- In Lizzie McGuire, Lizzie bonds with a bad girl in detention and starts going bad herself until her friends convince her she's a good girl at heart with a terribly made documentary.
- Party of Five:
- In the third episode, straight-A student and bookworm Julia convinces her friend to start going to parties during the week. The friend eventually has enough and disappears from the show but Julia keeps on with this new lifestyle and her grades start slipping. Her brothers try to convince her to go back to her goodie-two-shoes persona but she eventually finds a balance.
- Pops up as a joke in the second season where Charlie tells Kirsten she's a lot like her mother, prompting her to fret that she doesn't always make plans.
Kirsten: You know what, I was supposed to call the man about the invitations today. And you know what? I didn't. (claps hands) What the hell!
- Parodied in an episode of Scrubs where Elliott decides to go out on the town for the night. She steps out of a taxi and her hat is immediately stolen. She jumps right back into the taxi and screams "get me out of here".
- Malcolm in the Middle has Malcolm turning his brain off for one episode in an attempt to get with a ditzy girl. It works fine until he gets into a situation where his brain would have come in handy.
- In The Brothers Garcia Larry gets sick of being called a goodie two shoes and tries to throw a Wild Teen Party that predictably gets out of control.
- Wings provided the "Joe Blows" two-parter. Part 1 sees Joe so overwhelmed by being taken advantage of or constantly annoyed from all sides. So after thirty-five years of being the most responsible person on Nantucket, he finally loses it, gives an epic "The Reason You Suck" Speech and then steals Lowell's motorcycle to get away. By the time we catch up with him in Part 2, he's now partying and living it up in bars along the coast. He's basically become like Brian, who is now trying to keep the airline afloat and be the responsible brother.
- The How I Met Your Mother episode "The Pineapple Incident" has the gang convince Ted to drink instead of think. He wakes up next morning with a sprained ankle, burned coat, several drunken messages on Robin's phone and a girl he's never met before in bed next to him. Oh, and a pineapple for which we never get an explanation.
- On Buffy the Vampire Slayer, Willow gets a little fed up with her reputation as Old Reliable and flirts with danger a bit by doing a dark incantation with Anya. It doesn't end very well.
- In Family Matters, the strait-laced Laura is peer-pressured by her two friends to sneak into a strip joint. And naturally, she's caught by her mother...who later admits to having done a similar thing in her own youth.
- On New Girl, after Jess brings some furniture she found on the street home and Schmidt throws a hissy fit which culminates in destroying it, she insists its time for him to lighten up. Winston and Nick tell her its a bad idea to try to change him, but are too caught up in their own immature feud to stop her. Jess eventually does get him to unwind and he turns into a dirty, drum-circle-loving, crystal-necklace-wearing, slacked who no longer cleans up after everyone in the apartment, does all the shopping, or shows up to work. As the apartment starts to fall apart around them, Jess has and the others have to stage an intervention and lure him back to acting like himself with some (literal) fancy-pants. After he's back to normal, he's a little less uptight and accommodating (but not much).
- Emma in H2O: Just Add Water gets sick of being the responsible one and slacks off while her parents are away for the weekend. She eventually holds a Wild Teen Party and comes to her senses when her mother's crystal ornament is smashed.
- A season earlier, she gets annoyed when Byron calls her "dependable" and decides to colour her hair. The one Cleo gives her is called "Scarlet Fever". Luckily she's only stuck with it in her mermaid form.
- Good Luck Charlie Teddy finding out her nickname at school is GG (goody-goody) She tries to show she can be bad by drinking milk out of the carton. She refuses to swallow it, however, and runs to the sink to spit it out. Later on, Teddy makes a more earnest effort at being bad by ditching school and going to Super Adventure Land. After taking down a theft ring at the park, Teddy realizes she just doesn't have it in her to be a bad girl and embraces her goody-good image.
- The Kicks episode "Go Big or Go Home" involves Devin sneaking out with Mirabelle while the team is away at a tournament, contrary to her usual behavior.
- An inversion happens in the Bosom Buddies episode "WaterBalloonGate": Kip, who likes pranks, drops a water balloon from the apartment window onto a passing car. Said car happens to belong to Richard Nixon... and one Secret Service visit later, Kip not only decides to cut out pranking but becomes decidedly humorless and anti-fun until his friends get him to snap out of it.
- In Kim's Convenience, Janet starts to act rebellious when she feels she doesn't receive enough appreciation from her parents.
- There is an episode of X-Men: Evolution titled "Walk on the Wild Side" that plays with this trope. It involves all the X-girls and Boom-Boom forming a vigilante crime-fighting group, even Jean who is the responsible one. The Aesop of the episode is that fighting crime (with people willing and able to kill you and that can succeed if you're unprepared, mutant powers be damned) is not exactly the best place for a "You Go, Girl!" mentality.
- Susie in All Grown Up! gets told she's too perfect by the popular girls and decides to go bad for the episode. Angelica of all people tells her to calm down.
- In As Told by Ginger Ginger gets fed up of being called a nice girl and crashes a high school party. This leads to a rumour getting started about her and a bad boy called Jake. When she starts getting bullied for being "fast", Ginger realises she preferred being known as a nice girl.
- SpongeBob SquarePants has an episode where Squidward gets so fed up with Spongebob and Patrick's antics that he decides to move out into a gated community filled with other squids who share his interests. Inside, he finds that everyone else has a Easter Island head house, everyone else loves playing the clarinet, everyone else loves riding their paddlebikes, everyone else loves ballet dancing, and everyone else enjoys eating canned bread. He's thrilled at this, but soon gets bored of the same routine every day, to the point where he starts going out of control and just lets loose while playing around with a leaf blower. The other citizens filled a formal list of complaints, but Squidward tells them off by flying his leaf blower into the sky while screaming wildly.
- Hey Arnold! had this happen to Eugene, of all people, when he learns that actor portraying his favorite TV superhero is in fact a massive jerk.
- Avatar: The Last Airbender: Katara decides to pull a scam with Toph to prove she can be fun. It backfires, horribly.
- In The Simpsons:
- This happens to Marge on many occasions, ranging from running from the law with her friend after stealing her ex's car in "Marge on the Lamb", taking part in a monster truck rally in "Jaws Wired Shut", and gaining road rage from a Canyonero in "Marge Simpson in Screaming Yellow Honkers". Driving seems to be her recurring Berserk Button.
- In "Separate Vocations", Lisa becomes a delinquent after getting "Homemaker" in an Inept Aptitude Test and being told that she'll never become a professional Jazz musician due to her stubby fingers. This culminates with her committing an expulsion worthy offense (stealing all of the teachers' guides) to which Bart takes the fall, not wanting her to ruin her life.
- 101 Dalmatians: The Series had two episodes like this, both centering on Rolly:
- "Bad to the Bone" was about Rolly fooling Mooch and his gang into thinking he attacked Cydne the snake after being teased for being "soft", though he really only wrestled an empty snakeskin. After that, Mooch lets Rolly join his gang, and dubs him "Snake Stomper".
- "Walk on the Wild Side" was about Rolly becoming a con artist under Swamp Rat's wing, after the other pups accuse him of being a "sucker".
- One episode of Pepper Ann had Nikki doing this.
- In the Foster's Home for Imaginary Friends episode "Let Your Hare Down", Bloo finally gets Mr. Herriman to loosen up. The cast (except Bloo) quickly regrets this as the house descends into anarchy with Heriman's new hippie-like attitude to rules and life.
- One Dexter's Laboratory short has Dee Dee getting one Get Out! yell too many from Dexter and firing back a "The Reason You Suck" Speech that affects Dexter so bad that makes him decide to look for more zest in life, asking Dee-Dee to teach him. Unfortunately, when given the request to "go wild" on his laboratory (to show his "detachment from his earthly possessions" in the Zen way), he becomes such a demented savage that Dee Dee becomes seriously frightened and slaps some sense back into him, tearfully asking for forgiveness in trying to make Dexter something that he's not.
- In the Rugrats episode "Rebel Without a Teddy Bear", after Tommy's favorite toy lion is taken away, Angelica convinces him to go bad in order to get it back. Tommy's first bad act is to throw his empty juice cup on the floor. He soon escalates to real mischief with some guidance from Angelica.
- Steven Universe: In "Last One Out of Beach City" Pearl tries to act more rebellious, both to impress Steven and Amethyst and for her own sake (feeling that she's "lost her edge" since becoming a literal rebel). Pearl ends up leading the cops on a wild chase after running a red light to catch up with a "Mystery Girl" who caught her eye.
- On Beetlejuice, sweet little Lydia goes through this but not of her own doing in "Dr. Beetle And Mr. Juice." After getting spritzed accidentally with Beetlejuice's perfume concoction, Lydia transforms into a prank-playing troublemaking biker and paints the Neitherworld red.