Armor-Piercing Slap aka: Girls Hit Harder Than The Villains
His girlfriend is about to explode, and he's at ground zero, often without a bomb kit or a prayer. And when she slaps him, it hurts. Doesn't matter if he's Made of Iron, Nigh Invulnerable, or even completely invincible; it also doesn't matter how weak or powerless she normally is. He will feel the pain.
Maybe he honestly did something wrong, like cheating with another girl. Maybe the compromising position she found him in isn't really what it looks like (anything from being assaulted by a Clingy Jealous Girl to suffering an Accidental Pervert moment or even a completely Unprovoked Pervert Payback). No matter what the cause, she's hurt by his (apparent) betrayal and she won't stop until he feels her pain.
If he had no idea why she was angry, or if she were a stranger, or if he were a total jerk, he would defend himself. Which is why this trope almost never happens to anyone but the guy who knows exactly why she's mad (whether or not he's actually at fault), regularly associates with her, and is at least half-way decent. Even if this guy is a master martial artist and if she hasn't taken a single karate class in her life, she'll smack him silly because he all but lets her.
Why is the guy so powerless? Because it's a Double Standard. She's very, very angry — so angry that it frightens and intimidates him into a panic reaction. But he can't fight back, because he Wouldn't Hit a Girl. And he can't run away, because she'll just get madder and he'll have to face her eventually. He's stuck.
Even if he doesn't quite understand it himself, he instinctively knows that if she doesn't hurt him now, her wrath will fester into long-lived anger. Their association or relationship will be soured if not broken off altogether. Compared to that, a bit of mind-numbing pain seems the lesser of two evils — if she's allowed to take her pound of flesh, maybe she'll be more inclined to hear apologies or explanations later.
And so, the slap effectively pierces his armor.
Incidentally, the slapper doesn't have to be female and the slappee doesn't have to be male; there needn't be any sexual tension, unresolved or otherwise; and the attack may not even be physical at all. What matters is that a weaker person is slapping, scolding, or otherwise humiliating a stronger person...and the stronger person is so stunned - or ashamed - that he/she can do nothing.
Truth in Television, as anyone who interacts with young girls on a regular basis can attest.
See also Mundangerous and the Megaton Punch. Not related to Armor-Piercing Attack or Armor-Piercing Question.
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Anime and Manga
The Mazinger series had a good amount of slapping going around:
Sayaka to Kouji from Mazinger Z. Given that Kouji was the poster boy for tactless, Idiot Hero, and Sayaka a Tsundere, he found himself in the receiving end of these rather often.
And Jun to Tetsuya from Great Mazinger. Given that Tetsuya Took a Level in Jerkass when he was angry or upset, and Jun had little patience for stupidity, it is not surprising. A good example happens in the last episodes: Tetsuya is jealousy from Kouji, thinking Kouji will replace him and then everybody will forget about him. When Jun tried to reassure him it would not happen, he accused her of wanting to replace him with Kouji, too. She slapped him hard. Given that Jun had spent the whole series chasing after him while Tetsuya remained oblivious, it is entirely understandable.
Sakura to Naruto. Much more often when they were younger, and now, much more violently, considering Sakura's training under Tsunade, though Sakura and Naruto are closer than before and they are slightly more mature, so it barely happens in Part II (Naruto behaves less stupidly and Sakura is more patient).
Jiraiya mentions that he was nearly killed by Tsunade once before, for peeping on her in a hotspring. Tsunade broke both arms, both legs, six ribs, and "massive damage" to his internal organs. Just for illustration, Jiraiya claims that this was one of the only two times he had come close to death. It's also known that Jiraiya has gone on more suicidally dangerous missions than anyone else (138, to be exact). The women hit harder than the bad guys, indeed.
Subverted with Suigetsu and Karin. Karin tries to slap him whenever he badmouths her or Sasuke, but he just nonchalantly turns into water to avoid actually be hurt — she has to repeatedly start beating on his entire body just to genuinely annoy him (granted, that's not the way he uses his powers while fighting, but that's probably Rule of Funny).
I don't think these count, since the hit should send guys into some realisation and visibly emotionally affect them.
Misato slaps Ritsuko when she says that Shinji (the pilot's life) isn't NERV's priority after he is swallowed by the angel.
Misato slaps Ritsuko again when she continues to beat around the bush on the Eva's nature
Asuka slaps Shinji and his two friends after they accidentally saw her panties during their first meeting... and then she slapped Toji again when he pulls his pants down in retaliation.
Asuka slaps Rei when her confidence continues to spiral downwards and Rei confirms her obedience towards Gendo to the point of not fearing death and reminding Asuka of her disgust towards dolls.
Although Shinji has no armor when slapped things are awesomely- inverted in Super Robot Wars games: when Bright Noa slaps Shinji, Shinji starts to get his act together, gain a spine and a thicker skin, and gradually evolves into a Badass. There's a reason that such slaps were originally known as Bright Slaps.
Sae and Momo have slapped each other many times in Peach Girl.
Ranma ˝: Akane gives Ranma plenty beatings... but when she is seriously angry or upset with him, all that she does is slap him. Likewise, her slaps get Ranma more affected than any of her beat-him-to-the-ground-or-slam-him-in-orbit moments.
Partially justified as Akane Tendo comes from a family of martial artists who lives in a dojo, and is probably quite skilled, but only partially because the title character Ranma is one of the best martial artists around, who can easily beat her in a fight.
And Ranma is a Jerk with a Heart of Gold who often goes jerkass on her because of his raising and his macho behavior. He does care for Akane and is the first one to go help her if she needs it, but outside of these tight situations he just won'tspit it out or stop denying his attraction to her, and often he will go out of his way to tease her or mock her, therefore unleashing her violent side.
In Code Geass, Kallen does this to Lelouch for acting coldly about the fate of Japanese that work for Britannia. She later does this again, when a depressed Lelouch who is Not Himself tries to kiss her. Later on, she tries it on Suzaku when he tells her he's going to drug her for information, but it doesn't work. He backs down of his own accord, but that doesn't stop her from breaking out a 7 hit combo to voice her disapproval (and do what a good part of the fandom had been waiting for), in a dress, no less.
In truth, Suzaku lets her beat him up because he's trying to apologize, though when you consider what he's trying to apologize for, it comes off as almost insulting and stupid (she might have outright killed him were it not for her position), especially considering Kallen's mother became addicted to that same drug.
Himura Kenshin, the second most powerful swordsman in Japan in Rurouni Kenshin, can still be beaten into a daze by Kaoru... although it could be argued he's not bothering to fight back. (During a Clip Show, Yahiko notes this and decides that this must mean Kaoru is actually the best swordsman in the country... for some reason, Kaoru doesn't like the implication.)
A bit more realistically with Fuu on Samurai Champloo. Once or twice, she's given Mugen a good whack across the head with her wooden sandal.
This however, like several of the series aspects, is completely distorted within the proceeding manga adaptation. One bonus chapter featured her beating Jin (of all people) to such a bloody pulp that pixellation had to be applied to what was left of him.
In Fullmetal Alchemist, despite being one of the most powerful alchemists in the world and practically a martial arts master, Edward is victimized by Winry any time he visits. Her skillful wrench-tosses are the stuff of legend.
Bonus points for her being able to do this with Alphonse, who is a walking armor.
A rare serious use and discussion of this trope appears in Baki the Grappler, when the title character is facing a character, Yanagi, who is a renowned master of the open-hand slap. Baki remembers his father, the world's greatest martial artist, describing the slap as the one move that is effective anywhere on the body (as opposed to, say, a closed-fist punch which can break the attacker's hand if not aimed precisely). He further adds that his father said this technique was reserved solely for the self-defense of women and children. He then challenges Yanagi to a slap fight anyway, which leads to Baki ending up in the hospital.
Action Girl Sango slaps her Handsome Lech of a fiance Miroku, when he goes too far with his groping of her (or some other woman):
The Running Gag of 'Miroku gropes Sango, Sango smacks him' is performed often enough over the course of the series that at one point it helps bring Sango out of temporary possession by a flea youkai.
This little routine also shows up as a special combo move in the video game, where Miroku gropes Sango and ducks as she furiously swings her boomerang at him, which nails the enemy instead.
Another notable instance was when Sango was unconscious and Miroku needed to rouse her via CPR. However, she recovers just as he is about to apply lip service. The result was the scene pans out a good distance and a slap is heard, and the camera then returns to the two — Miroku's face is bright red from the impacting slap. Ouch.
Kagome deals out some slaps to characters who aren't even human, for example InuYasha himself. She might be a powerful Miko, but she's not really physically strong or fast enough to slap youkai, like when she slapped Kouga, a youkai, without using any spiritual power.
Iwata got the taste slapped out of him by Misaki Matsuya in Excel♥Saga when he suggested that getting changed in the locker room would give him an opportunity to see her naked body.
He got slapped into a vending machine so hard he demolished it.
Carrera Marker, mother of Karin Maaka, does this with a slipper whenever Karin does something very un-vampire-like and in every scene her husband Henry says something.
Probably because his own mother has her own Armor Piercing Slap
Anna's first meeting with Hao is actually a Double Subversion. She unleashes a slap on Hao, only for him to grab her wrist before she can do it, shocking everyone (including her.) Then she catches him off-guard with a Legendary Left.
There's a variant in Mahou Sensei Negima!, where Cheerleader Madoka slaps her unknown-to-her magically-aged teacher on behalf of her classmate, whom Negi had just walked in on while she was changing. She tries to do the same to Negi's also-aged rival Kotaro, whom she happens to have a small crush on, but he casually blocks it. So she punches him in the face instead.
Also done by the usually very calmChizuru to Noble Demon Wilhelm when he was about to petrify her newly adopted room mate Kotaro. Also, his petrification power is virtually impossible to heal, so she saved Kotaro's life.
Asuna does this to Evangeline (and Negi) a lot. It's also a literal armor piercing slap, as her Anti-Magic lets her punch right through magic barriers. Eva repeatedly complains about how Asuna is able to do that.
Negi himself doesn't always let girls slap him. At one point, he actually blocks Anya's punch.
Chisame does this to Negi when he is possessed by his Superpowered Evil Side during his meeting with Godel. It fully snaps him out of it despite the fact that the transformationwas triggered by Godel taking credit for Negi's entire village as a child. Seeing as this is the entire reason for Negi's dark-natured mindset, this is quite the feat. Here.
Subverted in Irresponsible Captain Tylor when, in the midst of being held hostage, Tylor tells Yuriko that she can hit him if she wants, offers her a briefcase to do it with, and then ducks when she swings. The briefcase hits the bomb-wielding terrorist, ending the crisis. He gets slapped at other times as well but doesn't have any armor to pierce. She never seems able to actually hurt the Captain, and he seems to like getting slapped by her to begin with
Souichi of The Tyrant Falls in Love, despite being male, can get away with this because his love interest (but don't ever tell that to him) Morinaga is also male. His more serious punches and kicks have left Morinaga bleeding and nearly unconscious, or with bruises that persist for several panels, though they're usually reserved for times when Souichi feels especially provoked or spurned by Morinaga; most of the other time, his physical violence is presented as harmlessslapstick caused by his cranky disposition.
In Full Metal Panic!, Sousuke has been beaten up often enough by Kaname to break out in a cold sweat as soon as he realizes she's angry about something. Even though Sousuke is a ridiculously skilled mercenary and Kaname is just a very athletic high school girl. And, as the second season clearly demonstrated, the only thing Sousuke apparently needs to keep kicking ass is being reminded what real pain is by Kaname. And damn, she's good at that.
Likewise, Kurz Weber takes a lot of well-earned abuse from Melissa Mao for his antics. In this case, however, it's much more sensible, given that Mao is a former Marine and Kurz's hand-to-hand combat skills are comparatively a bit lacking.
A non-comedic example occurs in the first episode of Sakura Wars TV. Sumire slaps Sakura for wrecking the Kobu kais before kicking her out of Flower Division.
Bleach plays the trope straight when Ichigo Kurosaki, depressed and guilt-ridden, lets himself be beaten by an angry Tatsuki Arisawa who feels that he has betrayed their friendship. It's slightly subverted by the fact that Tatsuki is probably the strongest Badass Normal around, but Ichigo is much stronger than her and could have stopped her if he wanted to.
Also subverted when Rukia Kuchiki, not above using force to get her way, decides to kick Tessai in the backside to get his attention, only to find out the hard way just how Made of Iron he really is. Not only does he not feel it, he only notices her when he turns to see her cradling her injured foot.
Again subverted when Orihime Inoue bitchslaps her jailer, Ulquiorra in the Arrancar arc. His skin is like iron, she just ended up hurting her hand.
Subverted in Dragon Ball Z. Chi-Chi, Gohan's mother and the main Tsundere of the series, walks up to Majin Buu (who just destroyed almost the entire population of Earth) and slaps him, berating him for destroying everything. His response? He calmly turns her into an egg, and steps on it.
During the American arc, when Ryoma acts selfish and rude by forgetting the team's needs, Tezuka straightens him up via a slap delivered in public. Later, his rival Kevin also is slapped by his American coach.
An Tachibana is a more straight example, trying to slap males twice to call them out on their behavior. The first time, Atobe catches her arm and tells her she's gorgeous when angry. The second, Kirihara tries to duck and falls down the stairs they were standing next to.
Let's not forget that, in Rokkaku, Bane slaps Dabide in public if he slacks in the courts. Or, if they're not playing, he kicks him in the head.
In the sequel to Kotetsu Jeeg, this is used as an actual (serious) attack by the titular mecha in the form of the Hell Slap which involves the Jeeg deploying spiles on its palm and igniting a jet on the back of its hand to deliver a powerful slap to the enemy. A variant of this involves the hand detaching and striking the enemies around it.
In Kyo Kara Maoh, Wolfram takes the time to verbally bash Yuuri's mother, calling her a Cheap Hussy. Completely pissed, Yuuri delivers a vicious slap to his face that sent the room into silence. Yuuri then learns to never do this again, because slapping someone's left cheek is a marriage proposal. So, he then became engaged to the very person who insulted his mother. Way to go.
A rare male-to-male example: In Initial D Second Stage, Seiji of Team Emperor, after his defeat at the hands of Takumi, gets slapped by Kyouichi, who follows it up with a "The Reason You Suck" Speech.
Early on in The Sacred Blacksmith, Luke Ainsworth gets a glimpse of Cecily Cambell's assets after the monster they were fighting had shattered her BREASTplate and the undershirt underneath. The ensuing embarrassment, egged on by Luke's Nosebleed reaction, prompts her to beat his face in savagely.
Possibly the most literal example comes from Macross Frontier, when Klan Klan, a Zentradi giant, get upset with Mikeal, slaps his mech so hard that it knocks him off balance.
Female on female example from Bokurano: Anko repeatedly slaps Youko while screaming "What the Hell, Hero??!" at her, after she's revealed as The Mole from another Earth and Koyemshi's younger sister.
Gankutsuou: A male on male example occurs in episode 2. When Albert tries to make light of almost having been killed, Franz slaps him.
In Vinland Saga, Canute flips out, after Ragnar's death and Askeladd gives him one of these. It shuts him right up.
Ash's Butterfree becomes the victim of a wing slap in Pokémon, coming from a female Butterfree that he was trying to court.
Ash also got slapped twice by Misty very early in the series for his immature behavior (both cut from the dub).
Subverted in Hunter × Hunter: Killua once got himself and Gon beat up by the lady operating the elevator at the Tower of Heaven. Later, Killua decides that, since he learned to use Nen, he's free to insult her with impunity, but it turns out she can use Nen to and gives him another beating.
Killua: I think she's stronger than Hisoka. Gon: How come I got hit?
In Soul Eater, whenever Spirit Albarn gets too weepy over his daughter, Shinigami will knock some sense into him with his "Shinigami Chop." Notably, unlike most uses of this trope the Shinigami Chop actually gets used seriously as a weapon, once, and it does an absolutely crazy amount of damage when Shinigami isn't messing around.
Maka's book serves a similar purpose for keeping Soul in line. Considering she calls it a 'Maka Chop' she most likely got the idea from Shinigami and her father.
Subverted more dramatically when Maka and Black Star get in an argument over who's holding back the team. When Black Star calls Maka weak, she tries to hit him and he blocks. When Maka tries again, Black Stars lets her hit him right in the face, takes it without even flinching, then tells her if she keeps it up he'll consider it an actual spar and feel free to beat the crap out of her. Tsubaki hits Black Star for that, and he agrees he deserved it, but it clearly didn't hurt either. Maka later admits trying to hit him in the first place was an overreaction, so they need to make things even between the two.
Subverted in Saikano, where an emotionally agitated Akemi gives Shuji a whack across the face. Shuji quickly regains composure and hits her right back, causing her to break down in tears.
In Popotan, Ai slaps Keith after she realizes that he's been lying to her about their relationship, which is enough to make him stop seemingly trying to murder Daichi. What she says afterwards is probably more effective than the slap itself, but it helped get the point across.
This is actually an accepted form of military discipline in the Universal Century Gundam works, where it is referred to as "correction." Zeta Gundam is probably the most slap-happy.
Kotetsu in episode 19 of Tiger & Bunny does this on an impulse as reaction to emotionally instable Barnaby's harsh words toward him, which were in turn a reaction to Kotetsu hiding the real reason behind his decision of retirement. Kotetsu would do it again in episode 23 with the intention to make Barnaby remember the above incident. An action rather lacking in foresight.
Allen Walker gets slapped hard by Linali in the earlier chapters (the Rewinding town) of DGrayman. He yells back though, but that's only being enraged point-blank, given it's Allen we're talking about.
A somewhat famous example from the Fantastic Four comics: following Ben Grimm's return from Battleworld of Secret Wars, he discovered that his old girlfriend, Alicia Masters, had taken up with the Human Torch in his absence. He and the Torch fought, only to have the battle end when Alicia slapped Ben. In later flashbacks, Ben comments that even though he could barely feel the blow, it was the most painful one he had ever taken. (A later retcon made this "Alicia" into Lyja, a Skrull replacement.)
The Spanish comic series Mortadelo y Filemon consists almost entirely of this trope with every character (including mooks) being both on the dealing and receiving end regularly. Usually it takes the form of a severe pummeling, occasionally involving weapons, and sometimes the panel shows the would-be recipient running or hiding from his pursuer.
Superman receives this in one storyline. While talking to reporters, a woman comes up and gives him one because her husband died of a brain tumor while Superman was off-planet, and Superman could have saved him. She even tells Superman that she knew it wouldn't hurt him, she just wanted him to know how it felt. Doesn't explain the fact that she blames him for something he had no way of knowing about. The crowd of reporters mentions that after she leaves, but by then Supes already started having his Heroic BSOD.
Princess Sally delivers one to Sonic the Hedgehog's titular hero after he decides that stopping Eggman is much more important than settling down with her.
Vartan: (to Jas) speaking of affairs, I was just wondering if you and Agrivar — <Ssslap>
Ishi: (talking to Agrivar about her outburst) ...which means that I still find affairs of the heart a mystery.
Vartan: (to Ishi) You know, I was just talking to Jasmine about affairs — <Ssslap>
Alice from Dilbert has a slap that's not just armor piercing, it's powered by Chucktanium. She once slapped Asok so hard that his face changed into a Dolphin's.
At one point during the Tamers Forever Series, Rumiko Nonaka slaps Takeru Takaishi in the face when he reveals that he plans to allow Takato to die so that Daemon won't be able to acquire the power of Chaos.
A Growing Affection starts with one, Hinata to Naruto, after she catches him mocking her (or so she thinks). She later gives one to Hanabi for badmouthing Naruto.
These fly all over the place in For His Own Sake, with varying levels of justification. In some cases, the slapper is in the wrong and upset over their target saying something they don't want to hear, such as Mokoto slapping Shinobu shortly before she and Naru try to beat the hell out of the younger girl. Played straighter when Kitsune delivers one to Kaolla Suu to stop her rampage at the Kuromitsu Inn, where she unleashes her robots on innocent bystanders just to 'liven things up'.
Megami No Hanabira: Sara earns one from Mai when she reveals she ran out into the demon-infested city to ‘train’.
Chinatown. An epic one given to Jake by the REAL Mrs. Mulwray.
Parodied in The Naked Gun 2 1/2, where Frank catches both of Jane's hands when she tries to slap him, only to have a third hand come up and smack him anyway.
The Master of Disguise: The Disguisey family used this as a style of martial arts:(consisting of slaps and blocks to humiliate your opponent). Pistachio took this form of combat to heart, Especially when his arch nemesis Devlin Bowman kidnaps Jennifer, & Pistachio's Mamma & Pappa. In the alternate ending, however, Pistachio decides to forego the slaps and simply punches Bowman out.
In Batman Begins, after the trial in which Joe Chill, his parents' murderer, is killed by someone hired by Falcone, Bruce reveals to Rachel that he was carrying a gun and planned on murdering Chill himself, but was beaten to the punch. She slaps him twice, and he does nothing to stop her, despite the fact that he's still holding the gun. Granted, this was prior to him gaining extensive martial arts training, but his complete acceptance of her punishment made the scene very effective.
Groundhog Day has a montage of these, since Phil continues to make different moves on Rita, and is continually shot down.
In Jaws, Chief Brody received a slap from the mother of the child killed by the shark after she found out he knew the danger existed yet opened the beach anyway. Since his decision was forced on him by his superiors, he reacted to the blow and her words with a vivid look of shame and guilt.
A slight and rather justified variation appears in I Love You Phillip Morris as a fairly effeminate Phillip slaps Steven after Steven faked his own death to get out of prison (again) and he comes back posing as Phillip's lawyer (again). Phillip was never supposed to find out about the fake death and Steven couldn't risk telling him the truth either.
In Some Kind of Wonderful, Amanda Jones smacks Hardy Jenns after he's tried to humiliate her and have Keith beaten up at his party. He stands there, flabbergasted, and she smacks him again.
In Star Trek Into Darkness Carol Marcus delivers one to her father after he beams her off the Enterprise before going forward with his plan to sacrifice Kirk and crew to instigate a war with the Klingons.
Indiana Jones receives one from his father in Indiana Jones and the Last Crusade. Henry insists on going to Berlin to retrieve his Grail Diary—vital to safely recovering the grail—rather than head to the Middle East to rescue Marcus, and when Indy tries to call him out on it Henry insists Marcus would agree. Exasperated, the younger Jones is about to take Christ's name in vain when Henry slaps him, shutting him up long enough to explain why getting to the grail first is so important.
Indy: Two selfless martyrs. Jesus Chr— *slap*
Henry: That's for blasphemy! The quest for the grail is not archeology, it's a race against evil! If it is captured by the Nazis the armies of darkness will march all over the face of the earth. Do you understand me?
In a flashback, Dagny, as a teenager, mentions to (also teenager) Francisco d'Anconia that she never studies but still gets straight A grades, and asks him if she should get D's just to be popular. Francisco is so disgusted he slaps her face hard enough to cause her to bleed out of the corner of her mouth.
Hank Rearden discovers Francisco in Dagny's apartment, but it's not because he's trying to seduce her, and offers him his word that he was not. Hank quotes Francisco's Oath ("I swear in the name of the woman I love that what I say is true,") after Francisco wouldn't help him when he despirately needed copper to make Rearden Metal, how, if Francisco gave his word in the name of the woman he loves, would he expect Rearden to believe it? Hank then realizes, that Dagny is the woman Francisco loves, asks him - despite Dagny's plea not to - and he admits it. Hank then slaps Francisco across the face in anger. Francisco, who cares deeply about Rearden, almost breaks the bones in his hands holding onto a table to keep from hitting or killing Rearden until his own moment of anger passes, realizing that Hank doesn't know what is going on.
In Harry Potter and the Deathly Hallows, Ron gets this from Hermione. Sort of an interesting subversion; if Ron had chosen to defend himself, Hermione could have bested him with magic.
The Reynard Cycle: Hirsent lands a good one on Isengrim during their reunion in Reynard the Fox. He takes it in stride.
In The Baron of Maleperduys she aims another one at him for endangering himself. He catches her wrist before it can land.
Happens all the time in A Song of Ice and Fire. Cersei in particular is fond of it; subverted nicely once when Tyrion decides he's tired of taking it quietly.
Near the end of Oblivion, one of the Spaceforce novels, Jay's commander Salthar slaps him so hard that he falls to his knees. And it cuts his lip. Salthar is furious that Jay eloped with a respectable Taysan girl while he was supposed to be pursuing the killer of the woman that Salthar loved, but could never have. Jay just takes it.
Played for Laughs in the episode "Fowl Play Date" of Happy Endings, while Penny and Brad are in panic mode because they killed Alex's racist parrot, Penny slaps Brad three times for being stupid/overly dramatic. He has this to say.
Brad: You know, the first two slaps I get, no notes on the those. But the third, like our ideas were pretty similar. If anything I got us in the area.
Penny: *Sarcastic slow clap* Congratulations Brad. You pitched an area. *She feints a slap and he flinches in fear.*
Say what you want about Glee as a show, but the slap that Santana gives Finn after he outs her is one of the best examples of this trope. It silences all the other 'gleeks' into stunned silence and brings a character who usually fights with words, insults and threats down to a level where she is so injured and exposed by his actions she finally stands up and puts him in his place, while all the while you see her breaking inside. Powerful stuff.
Subverted at one point on That '70s Show, where Jackie attempts this on Fez, who simply catches her hand before it can reach his face and berates her for trying it. It's okay though, because it's a joke about how effeminate Fez is.
In 24, Jack is on the receiving end of one these when Agent Walker questions his humanity. She also brings Jack's dead wife into it, and Jack, seeing how pissed off she is, manages to control himself.
Subverted, surprisingly, in Moonlighting: Maddie is mad at David because he tried to defend a man who had beaten his wife in the heat of the moment after seeing her with someone else. When David starts complaining, she slaps him... and immediately realizes the Double Standard in the situation.
Well to be honest, it would be hard to list all the times it has happened on EastEnders though it is worth mentioning that Peggy Mitchel is quite fond of it, as is Pat Butcher. People quite enjoyed it when they turned it on each other.
In "The Impossible Astronaut", River Song does this to the Doctor after seeing him die in his future, but her and the viewer's past, assuming the death she just saw was some sort of cruel joke.
A ridiculously exaggerated example is Mavic Chen slapping a Dalek for criticising him in "The Daleks' Master Plan". The Dalek is one of the cruellest aliens in the universe, it is covered with almost impenetrable armour, it feels no respect for Chen and is plotting his extermination, and yet the Dalek still reacts with confusion and pain (and an Aside Glance) before meekly following Chen out of the room.
Kamen Rider Odin commonly uses this as an attack. He even knocks over a truck with it at one point.
Noah's Arc: Chance gives one to Eddie during a heated post-cheating argument.
In Game of Thrones, Tyrion's slaps are the only things that seem to be able to make Joffrey behave and shut up. Contrast with his mothers' Cersei's slap which merely angers Joffrey.
Babylon 5 In the episode "In the Shadow of Z'Ha'Dum", Sheridan tricks Talia into walking down the same hallway as Mr. Morden, which causes Talia a great deal of mental trauma, putting her in Medlab. When Sheridan comes in to apologize, she slaps him in the face and storms out of Medlab. Bonus points for being an actual slap that actor Bruce Boxleitner wasn't expecting.
Erica Kane of All My Children dishes these out to great effect on both men and women alike. Her daughters get in on the fun as well.
Christian will occasionally tie his opponent up on the ropes and stomp on their back, then jump out of the ring and slap them in the face.
In the epic WrestleMania XXVI match between The Undertaker and Shawn Michaels, Michaels had just kicked out of a Tombstone Piledriver. He tries to claw himself back to his feet, to the disbelief of The Undertaker, who tells him to stay down. Michaels then mimicks Taker's signature taunt, and then slaps him in the face, causing the Deadman (regularly known for not selling) to stagger, before delivering a jumping Tombstone.
An example of how this can be an ACTUAL thing: Jim Cornette once did an interview, where he related the story of a wrestler who once got jumped by a ringside fan. Cornette (never known for his physical prowess) claimed the fan was so small HE could have beaten the guy up; the wrestler the fan jumped was "Hercules Hernandez". Being part of the pre-litigious era, the man was restrained and held backstage, and after returning from the match, Hercules slapped the fan so hard he knocked the guy off his feet, into the wall, and onto the ground unconscious. Cornette's group was the next scheduled match, they walked over the poor fellow, had the match, returned back and he was still out cold. Cornette asked Hercules why, if he was THAT angry, didn't he just punch the guy? The response: "Oh Jimmy, if you punch a guy you might hurt him!"
In Lunar: The Silver Star, Nash abandons the party and later prepares to fight them in a silly-looking suit of armor, now titled "Magical Weapon Nash." So Mia slaps him in the face, which snaps him out of it. It helps that the armor doesn't exactly protect his face to begin with.
In Overlord, your mistress or any female slaves administer one if you try to hit her.
In Tekken 6, Christie administers one to Eddy when she finds he's been working with the Tekkenshu in an attempt to get the Mishima Zaibatsu to give her grandfather (i.e. Eddy's mentor) the treatment he needed. Suffice to say that Jin never followed through...
Eternal Sonata inverts this trope by having Jazz (male) use an armor-piercing slap on Falsetto (female) in one cutscene. And then he hugs her. This scene also subverts the Double Standard which is closely tied to this trope.
Several of the female enemies in God Hand have Armor Piercing Slaps as attacks. Gene himself has a few moves (such as Pimp Smack) that might qualify as well.
Villainous example: MapleStory has Female Boss/Anego, a rather old-looking woman who can deal ridiculously heavy damage with a slap.
Virginia, from Wild ARMs 3, gets this treatment twice : first by her uncle, who slaps her because she tried to be a Hero and could easily got herself killed (well, rushing in a dungeon, all alone at level 1, filled with gobelins smugglers isn't the brightest idea), and the second time by Maya, a Drifter like her (but way more experienced), who gives her a What the Hell, Hero? speech after Virginia tried to pursue the antagonists and nearly got herself killed, save for the intervention of her comrade Jet, who she completely ignored while he just saved her life, which prompted Maya's slap. She quickly realised how naive and stupid she acted this time, thanks to Maya's speech.
In RuneScape, at the end of the "Garden of Tranquility" quest, when the King starts deriding all your efforts, the player is left thinking "Well, excuse me Your Highness!" Then, the Queen, who up until that point has been quite a bitch, steps up and requests to speak to the King privately. She delivers him an armor piercing slap (that delivers 10 LP damage), and tells him to be grateful.
The Doubleslap attack in Pokémon can be considered this in-game.
Wake-Up Slap is a better example. Not only does it do double damage to a foe if they are asleep (ramping up its already decent power), but it is Fighting-type, meaning it scores super effective hits against Rock- and Steel-types (the two tankiest types in the series), as well as Dark-types (some of the most ruthlessly brutal attackers).
In Final Fantasy V, having Lenna choose to kill the last wind drake to cure her mother results in King Tycoon giving her a slap that knocks her down, since Queen Tycoon has already refused to let her life be saved that way.
While escorting Meryl in Metal Gear Solid, if you decide to smack her in the face, she responds with a slap that, while only about as damaging as your punch to her (that is, not very) knocks Snake flat on his ass.
Though we never directly see one, Pearl Fey in the Phoenix Wright: Ace Attorney series is said to have a thoroughly powerful slap (she knocks Phoenix out at one point). She's a cute little girl in a comedic series of games that are ostentatiously anime-influenced. She's the most dangerous creature on the planet - except for all the murderers.
Sayori gets two Armor Piercing Slap moments in Yo-Jin-Bo. If you follow Yo or Mon-Mon's paths, Mon-Mon will try to garner sympathy (and thus, attention) by feigning a lethal injury. Upon discovering he's just fine, she slaps him. Or, if you follow Bo or Ittosai's path, Ittosai will make several comments about death and the uselessness of life, which angers her. Unlike Mon-Mon, it's surprising that Ittosai's only reaction is to protest that he's been slapped.
In the Tokimeki Memorial series, Kotoko of Tokimeki Memorial 2, being the Type A Tsundere she is, was the master at this, even going as far as slapping her own teacher, Kasumi (albeit for different reasons than love, unlike with the protagonist). And Suzune of Tokimeki Memorial Drama Series 2 : Irodori no Love Song delivered a powerful one to the Main Protagonist too.
An upgraded version is given to Walter by Tiren in Dubious Company. The cast teleport themselves to a Sci-fi universe. Before they can even get to the bridge of their Cool Spaceship, the Space Marines instantly declare them terrorists and attack. Walter becomes hysterical and begins shouting conflicting orders. Tiren punches him in the mouth to settle him down.
Bittersweet Candy Bowl has Lucy, who variously employs this on Mike and Paulo, the boys she likes. She becomes less violent over time as she comes to better grips with her feelings.
In The Inexplicable Adventures of Bob! when Molly and Golly have just met, and Golly has been picking on Molly relentlessly, Molly finally slaps her. It's a big emotional moment for both of them: Molly has never been mad enough to hit anyone before; whereas Molly was at that point the only person in the world that Golly even halfway trusted. (While, as clone-sisters, they're of equal strength, Golly is a fairly violent person, while Molly hasn't got a violent bone in her body.)
Near the end of Inverloch, Acheron learns that an elf killed his father and becomes very sullen, culminating in lashing out at Lei'ella by saying he doesn't care if all the elves die. She slaps him and calls him a hypocrite for condemning them all after saying so often that people shouldn't judge all of the da'kor by a few bad apples.
On Total Drama Action, Courtney seems to have no qualms being rather violent with her boyfriend, Duncan, whenever they go against each other in a competition. Duncan never returns the favor, although frankly, after she shoved a dirty diaper down his throat for absolutely no reason, one might forgive him if he did.
In Batman: The Animated Series when Ra's al Ghul is currently in Ax-Crazy mode after using the Lazarus Pit to revive himself, his daughter Talia delivers one of these to him to snap him back to his senses.