Ah, the age-old trope of someone not being as nice as they first appear to be. There a smorgasbord of ways for such people to reveal their true colors. Sometimes, however, all it takes is for another character to not be nearby to witness their actions.
Jerkass at your Discretion relates to a specific kind of Bitch in Sheep's Clothing that acts nice when certain people are within earshot, but instantly turn sour when they leave. These kinds of characters tend to come off as particularly mean, since their desire to hide their true nature implies that they're aware that their behavior would be considered socially unacceptable, but barring one or two exceptions, they simply do not care.
This kind of character tends to be a fairly mundane Villain of the Week, as the "only nice when X character is around" gimmick would get old pretty fast if it isn't resolved. Often a plot involving a Jerkass at your Discretion has the object(s) of their ire trying to warn others of their true nature, only to get brushed off time and again, usually ending with the person from whom the JAYD is trying to hide their true nature finding out one way or another, and subsequently severing ties. Expect the JAYD to thoroughly abuse the tried-and-true Wounded Gazelle Gambit and the False Innocence Trick for all they're worth, taking every chance they can get to make the one person aware of their true nature look like they're the bully.
Truth in Television, as this is a textbook tactic of abusers and bullies. Many abusers carefully maintain a positive and well-liked public image as a way of isolating their target, as (theoretically) the target is less likely to be believed if they report the abusive behaviour to others. This is a main reason why survivor advocacy groups have focused so strongly on a message of "believe survivors (when they disclose abuse)" in recent years.
Contrast Jerkass to One, where a character genuinely is nice most of the time, and is only mean to one specific character, Tsundere, where a character acts mean to their love interest in an act of denial when talking to them up front, but secretly shows their true nicer feelings to them when they're usually away, and Yandere, where a character has an infatuation/obsession with someone they claim to love, but will threaten anyone who gets in the way of their desire (the love interest, if needs be). When a character maintains a facade despite being alone, see Undercover When Alone. Related to Two-Faced Aside when someone says one thing in front of someone and then expresses the opposite when out of their earshot, Nice Character, Mean Actor, when they act nice on camera but are mean when they're not rolling, and What You Are in the Dark, when they only show their true colors when they're completely alone. Compare Morality Pet when a Jerkass acts genuinely nice due to a select person's influence. Compare Traitor Shot.
- In Toradora!, Ami Kawashima is a high-school Fashion Model that seems very sweet and clumsy to everyone else in order to get accepted by her peers. Only her childhood friend Yuusaku Kitamura knows her real self: an arrogant girl who will not hesitate to use abusive language towards others, and tries to make amends if someone sees her true personality, because she is uncertain about her dual personality. This personality is shown early to Taiga Aisaka (who tried to break up the facade for everyone and became rivals), Ryuuji Takasu (who understands her and even got her to fall in love with him) and Minori Kushieda (who has a bigger facade than her and that pissed her off).
- In The Hand That Rocks the Cradle, Emma has to deal with a schoolyard bully of this type. To clarify: he is a huge braggart around other kids at recess and targets her specifically, but puts on his nice sweet face whenever authority figures are anywhere to be found. While these figures are never shown finding out, Emma simply points him out to Peyton, and it's all over for him.
- Mean Girls: Cady first realizes what a true Bitch in Sheep's Clothing Regina is when she deliberately calls out to another girl to compliment her on her skirt, only to immediately turn around and call it ugly to Cady as soon as she walks away. This causes Cady to remember when Regina had also said something nice about Cady's bracelet, which she'd assumed was genuine at the time but now no longer trusted.
- Ore wo Suki Nano wa Omae Dake Ka Yo:
- High school student Joro is an Ordinary High-School Student and Clueless Chick Magnet who is close friends with both his Childhood Friend Himawari and Student Council President Cosmos, who make subtle passes at him which go over his head. One day, both girls ask him out on dates, where they confess that they're in love with Joro's best friend, Sun-chan. When Joro is out of vision and earshot of both girls, he reveals that the Oblivious to Love Nice Guy persona was all an act to get both girls to like him so that he could have a typical anime harem. Joro's real personality is closer to a Jerkass Japanese Delinquent with an extremely vindictive and manipulative streak.
- Later, it's revealed that Joro's best friend, Sun-chan holds an intense grudge against Joro for unknowingly "stealing" the affection of a girl Sun-chan used to like in middle school. Sun-chan thus deliberately attempted to (and for a brief time, succeeded to) ruin Joro's relationship with both Himawari and Cosmos as revenge. Ironically, though, Sun-chan is foiled when another girl he has interest in, "Pansy", is again in love with Joro and thus creates and Engineered Public Confession that outs Sun-chan's plan to Joro, Himawari and Cosmos. When he thinks no one's around, Sun-chan even threatens to rape Pansy for not returning his affection, until Joro appears and punches him out.
- Overlord (2012): Princess Renner is considered The Golden Princess by her people and has a 100% Adoration Rating by the masses. But in reality, she is a complete and utter sociopath without a single ounce of empathy. Her only "redeeming" quality is that she is absolutely in love with her bodyguard, Climb, and will do anything to marry him and make him the father of her children. Her sole reason for putting on the act of a benevolent princess is that it makes Climb love her; in one scene, Climb turns away from her just long enough for us to see this face.
- Brooklyn Nine-Nine has a subplot in one episode where Boyle arrests a very old man on suspicion of robbing a bank. When he's just with Boyle, he's a Smug Snake who proudly boasts about his crimes and how he enjoys inflicting terror on his victims, but when Amy and Rosa are present, he pretends to be a sweet and frail gentleman, causing them to think Boyle is the one being a jerk for arresting someone seemingly incapable of committing such a serious crime. The robber ultimately dies of old age before Boyle can get a (official) confession out of him, but the girls are ultimately convinced that he got the right guy anyway due to a dollar bill the old man gave Amy having the same serial number as the bills stolen from the bank.
- In Cheers, Frasier Crane is proudly introducing Diane Chambers to his mother as his intended wife. When Frasier or other members of the core cast are present, Hester Crane is benevolent and loving towards her prospective daughter-in-law, and seemingly supportive and approving towards her. But in private, Hester expresses her true emotions, and malevolently tells Diane she disapproves and intends to shoot her through the head and make it look like an accident. As Diane already has a reputation for being a self-centred Drama Queen, she knows she is going to be disbelieved if she complains.
- One episode of The Golden Girls, aptly titled "Little Sister," introduces Rose's younger sister Holly. Rose admits ahead of time that she does not like her, and we soon see why. Holly acts perfectly polite and charming (to the point of overdoing it) when Rose is with Dorothy, Blanche, and Sophia, but whenever the other girls try to arrange plans for them all to spend time together, Holly deliberately withholds the information from Rose and then claims that her sister simply doesn't want to spend time with her. Sadly, Dorothy and Blanche grab a firm hold of the Jerkass Ball in the episode and, despite seeing Rose as family, won't believe her when she says that Holly is deliberately manipulating the situation. Only Sophia is able to see what Holly is up to, but the others don't come around until she starts fooling around with Blanche's boyfriend, proving that her rotten character isn't limited to Rose alone.
- House of Anubis: When Patricia and Fabian both turn into Sinners, they continuously pull this trick to torment their chosen victims further. Patricia revealed her true nature to KT, only to then act like the victim of KT's "evil" whenever the rest of Sibuna was around. Fabian, meanwhile, was as friendly as usual to KT, but whispered cruel things to further break an already hurt Joy, and then proceeded to reveal his evil nature only to mock Alfie's attempts at stopping him — all the while KT was none the wiser.
- Wade Collins acts like a reasonable enough guy when on camera, even possessing a sympathetic story about a chronically ill mother. The moment the cameras go off, however, he instantly begins acting like an entitled snob who has no true passion for music and is Only in It for the Money. It also comes out that he lied about his mother being sick specifically so he could get the crew's help to make his music video. They ultimately get their revenge by exposing him to millions of viewers on their web show.
- In "iReunite With Missy", we meet Carly's old best friend, Missy. She seems genuinely nice to everyone, if causing a lot of accidental misfortune for Sam...at first. As soon as Sam is alone with her, she starts openly taunting and bullying her, only turning on the charm when Carly is back. Carly only learns the truth when she accidentally catches her making fun of Sam when she thinks the two of them are alone. What solidifies her as this trope instead of a Jerkass to One is that Missy barely cares when Carly catches her and immediately sides with Sam, and is more ecstatic about the cruise trip she just won.
- Fire Emblem Fates features a variant of this trope with Charlotte, a Nohrian border guard who acts like a sweetheart when around most other people, but is her regular, much less pleasant self around her friend Benny. Unlike most of the other examples of this trope, Charlotte and Benny actually get along quite well, and she finds it relieving that there's someone she doesn't need to put up a front around. Part of her character arc throughout her supports has her either Becoming the Mask, or learning to embrace her true self.
- In Persona 5, this is played with. At first, it seems like Kamoshida managed to hide his abuse towards the volleyball team by acting completely upstanding when in public. However, it's revealed that all of the adults, including the principal and the parents, already know and choose to cover it up because of the stellar reputation he brings to the school. Most of the students (barring those on the volleyball team and the other sports teams that were disbanded) are still unaware, though.
- The Boondocks: In "The Block Is Hot", when Jazmine sells her lemonade stand to Ed Wuncler I for a pony, he acts perfectly reasonable about the arrangement... Until he sees her father Tom walk into the house. At that point, he begins rudely berating her for every minor slight, and soon forces sweatshop working conditions onto her. Tom catches on quickly and tries to stand up for his daughter, but is strong-armed into backing down when Wuncler threatens him with gang violence.
- One episode of Doug features Mr. Bone's nephew Percy coming to town and acting like a royal jerk to everyone he meets—to the point that even Roger thinks he's a complete monster. Percy covers up his nasty behavior whenever his uncle is around, though, so it's hard for him to get punished; it takes Roger tricking Percy into bullying Doug when Mr. Bone is nearby to get justice.
- Golan the Insatiable: In "I Can Smell That Cheap Clone From Here", Golan inadvertently gives birth to a duplicate of himself which unlike him, is a Kindhearted Simpleton who everyone loves. When nobody else is around, Clone Golan reveals that it's all an act to gain people's trust and he is actually just as evil as the original and even more intelligent and ambitious, devising a plan for both of them to take over Earth. Golan kills him after being told that he has to apologize to Dylan to build up his reputation in order for the plan to work.
- This trope is famously inverted with Helga Pataki of Hey Arnold!. Helga acts like a complete jerkass whenever anyone, but especially Arnold, is within earshot. But as soon as she's alone, she reveals a poetic, romantic, and deeply wounded soul. Later episodes reveal that her emotionally abusive and neglectful parents have created a Freudian Excuse for the ages—Helga feels that she must put up a tough veneer to keep people from seeing her as weak and helpless.
- Lila Rossi in Miraculous Ladybug is a Consummate Liar and a sociopath, being a much more toxic (and hauntingly realistic) influence to those around her unlike the Obliviously Evil Chloe or the over-the-top Hawk Moth. A recurring tell Lila has is when Lila drops her charming Nice Girl smile in favor of a contemptuous scowl whenever the person she is talking to turns their back on her.
- South Park: Played With. In earlier episodes, Stan's bully big sister Shelly beats him up every time the parents aren't around. However, Shelly's facade tends to be half-hearted at best, with several occasions having her openly assault Stan in public, implying the gag is less that Shelly is manipulative and more their parents are incredibly incompetent.
- In the SpongeBob SquarePants episode "A Pal for Gary", SpongeBob buys an extremely cute pet from an old lady so that Gary isn't lonely, ignoring the lady's warnings that it shouldn't be near other pets. When he brings Puffy Fluffy home, it seizes every opportunity to terrorize Gary whenever SpongeBob isn't in the room. Each time SpongeBob comes back, Puffy plays innocent and poor Gary ends up taking the blame for whatever events transpired while he was out. And even when he finds out that Puffy Fluffy is indeed a hideous monster, he still chooses to blame Gary.