Another example would be when Nagasumi grew giant after taking a mermaid drink and rampaged around without Magic Pants, one method of attack used against him was crashing a submarine out of the ground and RAMMING the tip into his...well, you can guess where I'm going with this.
An unfortunate case of a doctor getting this treatment occurs in Magikano.
In the H-Manga Blue Eyes the main character Tatsuya orders a dog to sic on a would-be-rapist. The dog goes for the obvious weak spot.
Android 18 did this to Vegeta, likely her CWA. It actually stunned him for a while, giving a time for her to toy with him a bit before she gave him another punch to the side.
Dragon Ball GT features the rare Double Groin Attack, where the main character kicks one groin while elbowing the other. Superb technique.
One of the actual Z movies, Dragon Ball Z: Super Android 13!, further proved its effectiveness: after the Big Bad powers up to his super form, Goku and Piccolo go for the usual rapid punches and kicks assault: Piccolo ends up knocked away in some unremarkable way, but Goku isn't quite as lucky. The Big Bad counters him by grabbing his high kick with one arm and punching him in the crotch with the other hard enough to cause him to fall down and out of Super Saiyan mode immediately.
Garlic Jr. gets one in the first movie courtesy of Piccolo.
The original Dragon Ball series! Yamcha was unlucky enough to get an especially painful one during the Tenkaichi Budokai. And from Shen aka Kami possessing a random passerby's body and making him a Badass Normal for a while nevertheless. Poor, poor Yamcha. Normally groin attacks are grounds for immediate disqualification in the Tenkaichi Budokai, but the judges ruled it was an accident (Yamcha went for a jump kick, Shen ducked, and groin hit head) so Shen was allowed to continue fighting, although only after Yamcha was given enough time to recover.
This happened to Mister Satan once as well. He landed crotch-first on something pointy...ouch.
It also happened to Gohan in the Dragon Ball Z Episode 251: The Old Kai's Weapon, thanks to Super Buu after he absorbed Gotenks and Piccolo.
Arale headbutts General Blue in the groin in Dragon Ball.
A gender-inverted one happened to Chi-Chi in Dragon Ball. Although it doesn't appear painful, while Goku and Chi-Chi (as kids) were flying on the nimbus, Goku (lightly) kicked her in the groin to see if she was a boy or a girl. Chi-Chi then pushed him off of the nimbus as a result.
In Dragon Ball Z: Resurrection ‘F’ at one point during their fight after he has reached his ultimate form Frieza flips Goku over and knees him in the groin.
One happens in Dragon Ball Super, when Tagoma boasts that being Frieza's sparring partner for four months has made his body harder than steel and sophisticated attacks have no effect on him... and Gotenks promptly headbutts him right in the Dragon Balls (likely the one place Frieza did not attack him into in those four months), for devastating effect. Muten promptly states it wasn't a sophisticated attack.
Bel in Haré+Guu delivers one to Asio after he points out her lack of attentiveness. When she attempted it later Asio blocked it.
Fairy Tail: Lucy had been captured and is being held in the Sky Prision. After the Phantom Guild's master, Jose, is finished taunting her, she says that she has to go to the restroom; Jose, actually being pretty smart doesn't fall for it. Instead, he simply points to a bucket that was sitting in the cell and says "Go ahead." thinking she wouldn't degrade herself in such a manner, being the daughter of one of the richest families in the world. She proves him wrong and, much to Jose's surprise, goes to use the bucket. Jose, being a "gentleman" turns around so as not to watch and Lucy takes advantage of this and delivers a swift kick to his nuts and bolts.
He even does this against mecha, as seen when he shoots the Behemoth between the legs. In this case though, it's justified, since that's where the thing's cooling system was located and Sōsuke was trying to force its Lambda Driver to overheat and shut down.
During Luffy's first fight with Buggy the Clown, while Buggy's upper-body is busy chasing Nami, Luffy kicks Buggy's lower half in the groin, prompting Buggy to lament what a cheap shot that was. Only minutes before, Luffy had stopped Buggy from interrupting in Zoro's fight with Cabaji. Apparently, holding someone still so that your subordinate can finish them off is cheap, but a nut shot isn't... Then again, I Am Your Opponent seems to be the only rule of fighting that Luffy cares about.
Later on, Nico Robin performs a long-distance groin-grab on Franky in order to recruit him to the crew. Everyone else, men, women and children, react to this with appropriate horror. To quote a random female bystander, "I feel sorry for him...but he's still a pervert." What makes it even funnier is while she makes this attack, There's a sequences of repeated reactions with people saying something like "She's got him by the-" and then there's an insert shot of a piece of fruit.
Emporio Ivankov actually heals Mr. 2 Bon Clay through a groin attack. He was injecting his "Emporio Energy Hormones" and aimed a little higher than intended...
Apis, while trying to escape from the Marines who kidnapped her, accidentally kicks a soldier in the crotch. The poor guy stood absolutely motionless after that.
During the Alabasta arc in the final battle Nami does this to poor Usopp who gets hit with both a stick and an explosion to blast Chopper and Vivi to the top of a clock tower where a giant city buster bomb is located.
Get Backers: Sweet little blind violinist Madoka Otowa does this to one of the guys who are holding her Stradivarius captive. In the dark. It's mostly off screen, as we only see her smiling brightly, then the guy hopping up and down in pain, but still...
Gintama has plenty of these. Gintoki falls victim to them the most, which might be related to the fact that the title of the manga is partly named after him and is only a letter off from being the Japanese word for the abused body part in question.
One of the "tricks" Kagura teaches Sadaharu for a pet show has him knock Gintoki and Shinpachi down, then stomp on their groins. Repeatedly.
Domestic Violence, the signature move of the Gintaman manga's titular character, is one of these taken Up to Eleven.
Gintoki actually gets his balls knocked off by a particularly brutal one during his bout in the Shikigami tag-team death match. They then proceed to get abused even further when Doman and Seimei decide to have them battle by taking control of them and ramming into each other before they finally end up getting crushed into a bloody pulp by Gedomaru in response to him asking her to make it stop.
In one episode of The Tower of Druaga: The Aegis of Uruk, Coopa is changed from a girl into a boy as a result of a magical trap. In desperation, she hits herself in the groin...with very painful results.
An example of the very rare female form of this occurs in The Tower of Druaga: The Sword of Uruk, when Ki does it to Fatina with a spoon. From Fatina's reaction, Ki did hit the right spot.
Kon in Ichigo's body gets one from Rukia, with him lying on the floor, apologizing to Ichigo for having it so that Ichigo won't be able to have kids anymore.
Played straight in the anime, where Ganju Shiba does the "lift his legs, repeatedly stomp" variant to Ichigo during their second fight after they meet again.
Tessai used this particular maneuver to punish Jinta for slacking off (or was that Jinta imagining how Tessai would punish him?). In the anime at least it absolutely happened as Jinta's flashback only occurs after Ururu reminds him of it.
After rescuing Orihime from Grimmjow, she asks Ichigo if she's too heavynote he's got her slung over his shoulder and he tells her "You're not as heavy as I figured". In response to this, Nel punches Ichigo in the crotch for being rude to Orihime.
Anime episode 207. Lieutenant Hiyori Sarugaki of Squad 12 tries to knee the squad's new captain Kisuke Urahara in the groin because she's seriously annoyed by his personality. Unfortunately it ends up backfiring on her: he wears some kind of hard protection (or else just has Balls of Steel) under his clothing and she ends up being the one in pain, hurting her knee. She later tries to do it again but stops at the last moment, recalling what happened the first time.
Anime episode 226. Captain Soifon tries to hit her annoying lieutenant Marechiyo Ōmaeda in the face but he blocks the blow and taunts her. She then hits him in the 'nads.
A flashback scene in Glass Fleet shows then-teenaged Cleo resorting to grabbing and squeezing in order to win a fight with another boy. Previously, Eimer also used the standard groin kick to stave off Attempted Rape at the hands of a group of prisoners, but that wasn't played for as much comedy.
Several transgendered variants show up in Ranma ˝:
The standard Groin Attack was used, albeit unwittingly, exactly once: Ranma's ankles are tied to Akane and Shampoo's, respectively when they try running down separate corridors. Ranma, stuck in the middle, is pulled straight into the the corner (though he hits his head and his torso at the same time.)
In episode 38, angry that Genma landed in his panty collection, Happosai responds by kicking him in the groin and knocking him unconscious with a blow to the head.
In episode 104 Sasuke attempts to abduct Ranma while he's in female form when he's sleeping. He starts to tie up his arms when suddenly his leg shoots up and knees Sasuke in the groin.
In episode 140, when Ryoga defends Akane from Happosai's six devils and they gang up on him, the centaur one headbutts him in the crotch.
The Katekyo Hitman Reborn! anime uses this in the second episode for cheap laughs. Apparently Tsuna failing at playing volleyball then suddenly doing well wasn't entertaining enough: he had to start playing volleyball with his groin. And so, Reborn is an asshole as usual.
In fact, Yahiko invented a technique in the Jinchu arc called "Kamiya Kasshin Ryuu: Curse on the Descendants" which is essentially a flying sidekick to the groin.
He bit a guy in the groin in the manga. In the same chapter in which he was introduced.
Episode 17 of the Anime series had the Girl of the Week Marimo kicking the episode villain's henchman in the groin from behind as she and Yahiko were confronted by them while making their way back to the circus show. It's no surprise that the henchman was hopping up and down in excruciating pain while holding his crotch after Marimo's surprising kick and that both Yahiko and the villain were quite surprised to see such an event transpire.
At one point in the manga, Yahiko isn't watching where he is going... and walks headfirst into Sanosuke's groin. It Makes Sense in Context: Yahiko is really short, and by contrast Sanosuke is the tallest of the group.
Happens most unexpectedly in Chapter 41 of the Ga-Rei manga when Kensuke goes to check on Yomi, and quickly regrets it.
In Zatch Bell!, the melon-chomping V-shaped Victoream has shiny balls on his arms, either side of his head and at the tip of his V. When he gets tied up after his "Very Melon" song, Tia stomps Victoream repeatedly on the tip of his V, leading him to remark in the Japanese version "Don't bully my gentleman!"
An early chapter has Setsuna attempt a variant of this which is too horrible to describe, especially since she does it in a furo...to her ten-year-old teacher. And they're both naked. Cue Blank White Eyes. At least she had the excuse of not knowing that it was him and being scared off when he got in the bath.
Setsuna: Eh...um...this...I mean...well, to aim for a vital spot is basic theory and... I'M SORRY SENSEI!
There's also Haruna's imagined punishment for her (female) friends for keeping up The Masquerade against her; she illustrates it to them with manga pages involving them hanging upside down, panties exposed.. and Haruna has a whip and a good sense of where to aim... immediate genuflection follows.
Setsuna herself is subjected to one over 200 chapters later, courtesy of Evangeline. Also seehere.
Episode 6 of Slayers NEXT had Martina place a curse on Lina, in which any pain she inflicts on others is magnified and directed back at her. Naturally, she ends up kicking Gourry in the groin after he had accidentally grabbed her breasts (courtesy of Xellos) and made a remark about how small they are and...well, Hilarity Ensues.
Episode 14 of the original City Hunter had Saeko kidnapped by members of a local gang who's abducting beautiful young women. In her prison cell, Saeko gains the attention of a nearby guard and upon distracting him through the use of her sweet talk, Saeko kicks him in the groin, managing to get the cell keys from him while playfully apologizing about her deceptive kick.
At the beginning of the original series' Episode 43, the Girl of the Week, Utako Yumeno, knees a man in the groin from inside a train after he had suddenly bumped into her and accidentally looked down her shirt.
In the manga a punk once tried to kick Ryo there. Ryo immediately hardened his Gag Penis, breaking the punk's foot.
The first episode of the Dirty Pair Flash OVA series had Yuri kicking a leading police officer in the groin after he began to harass her about an item that she had gotten from a recently deceased man. It's safe to say that his teammates weren't too pleased to see this and that they eventually went after Yuri, who somehow got Kei involved in the chase as well.
The eighth episode of Burn Up Excess had a giant Rio dealing with a giant male transvestite as the two of them were battling in the city from within a Neon Genesis Evangelion-like parody battle. Near the end of the fight, Rio ends up delivering a devastating back mule kick to the guy's own groin and you can't help but feel sorry for him, since Rio (a trained martial artist) struck him with a sharp high-heel shoe and that you could hear the direct Sickening "Crunch!" of the man's own crotch (complete with an x-ray that shows the entire pelvis cracking itself). It's safe to say that it's gonna be a long time before the guy is able to recover from such a strike.
Episode 19 of Trigun had Meryl delievering a swift groin kick to a random Mook who got close to her after hearing something about a typhoon (which was possibly a reference to Vash the Stampede).
Episode 26 of MÄR had Jack winning his rematch against Pano through the use of some hallucinatory toadstools that made Pano see Jack as being some sort of handsome guy. When the effects had wore off, Pano was less than pleased about Jack manipulating her normal senses and she ends up kicking him in the family jewels, much to Jack's dismay and to his own teammates' embarrassment.
The third episode of YuYu Hakusho had Yusuke (in his ghost state) taking control of an unconscious young teenage schoolgirl's body so that he can protect Kuwabara who was on his way to school. During his fight against the school thugs that had tried to attack Kuwabara, Yusuke (in the body of the schoolgirl) is able to battle and defeat each of them with no problem and in the end, he delievers three groin kicks to the last thug before knocking him out with a hard right punch. Afterwards, Yusuke leaves the body of the young teenage schoolgirl, who is quite shocked to see on what has transpired.
Kurapica [touching his lips]: Whew... I was lucky she didn't choose me.
The second episode of Bastard had a ninja master named Gara infiltrate the castle of where the protagonists were currently staying from. Upon entering into the room of where both Luche and Yoko were sleeping in, Gara is quite surprised to see that Yoko is able to detect his presence and that he decides to introduce himself to her in an instant, but Gara is immediately cut short of his own introduction speech when Yoko throws a quick back mule kick to his groin from within an unexpected and surprising manner.
In one episode of Crayon Shin-chan, Shin's little sister Himawari has just had a cup of juice and wants more, but her mother Misae won't give it to her. Desperate and determined, she tries with all her baby might to reach and open the refrigerator, where her beloved juice awaits. After she utterly fails and exhausts herself, Shin-chan comes in from playing, sets up a chair in front of the fridge, and helps himself to the juice. An enraged Hima charges him like an angry bull, and headbutts him in the crotch with enough force to send him flying out the door.
Mugen gets one of these when he comes on too strong to an female undercover ninja (to be fair, she was undercover as a prostitute). This backfires, as after he crumples to the floor he gets back up and declares that he likes a girl with spirit.
In the last episode, Mugen is holding the bad guy in this weird upside-down wrestling hold, and if you look close, he's also biting him in the crotch. Call it badass or Squick, but remember that Mugen is at heart a Combat Pragmatist.
Way back in the first episode, Fuu kicks a random guard in the groin while he was distracted by Fuu's pet flying squirrel, Momo.
In the first episode of Mezzo DSA, Mikura kicks a Mook in the crotch with a clean kick. The visual metaphor of two gold balls shattering to dust is seen before the poor sap goes flying through a wall.
In Beelzebub, Oga, the main character, is surrounded by some of his high school's strongest brawlers, who challenge him for carrying a baby on his back (the baby in question? The son of the devil, sent to earth to learn to be evil from the most evil human alive, Oga, while he grows up, but they aren't to know that.) Oga's response? The first two that attack him both get an instant punch to the groin as he walks past them. In a later chapter, when a policeman threatens Oga with the law, then turns around, Oga kicks him in the crotch hard enough to lift the policeman up.
Almost to the end of the second episode of Puchim@s, Afu runs toward Mr. Producer, leaps up... the top of her head slamming into his crotch. Immediately, his legs wobble and buckle before he falls down on his knees.
Tengen Toppa Gurren Lagann has a variant of this happening. During the fight in the ocean with Adiane, the extremely phallic mobile base gets its main underside cannon destroyed. Every male except for Camp Gay Leeron grabs their groins in pain.
Not even Sonic X is immune. When Emerl goes berserk in the Sonic Battle arc, Sonic tries to fight him off, as Emerl issues one of these onto Sonic. We then see everybody's horrified reactions. Made even funnier when Sonic tries to take it like a man (err, hedgehog) despite being in immense pain and his voice getting higher. He faints anyway. Surprisingly, 4Kids left it in, but unsurprisingly, they found another way to work around it.
In the OAV Sonic the Hedgehog: The Movie, towards the end of the film, Sonic falls onto the upraised prow of a hover-ship crotch first and promptly starts reacting in silent pain. Robotnik is baffled by Sonic's antics, then notices that Sonic's robotic doppelganger (which has embedded itself in the hover-ship's underside, so its head is sticking out of the floor) is getting kicked in the head by the Cat Girl, who's accusing it of trying to look up her skirt, and claims that Sonic must be trying to synchronize with Metal Sonic.
In episode 4 of Baki the Grappler, when Baki is fighting (and losing) against The Beast of Yasha Crag, he tries a groin kick against the ape, which he finds to be effective. He then continues to kick the creature repeatedly in the genitals as hard as he can until it finally throws him away.
In episode 15 of Dragon Quest: Legend of the Hero Abel AKA Dragon Quest I - Yuusha Abel Densetsu, Mokomoko (also known as just Moko), the rotund, hairy barbarian, falls from a great height, and he lands groin-first into the open jaws of a sea creature, with it's fangs pressing against his crotch. There is a funny 'boing' sound, and he flails his arms around with a pained expression.
Episode 15 while training Sadaharu (the giant dog) for a show, he crushes Gintoki and Shinpachi's crotches. Kagura cheers him on ...
The chapters involving the warring Ketsuno and Shirino clans dealt massive damage to Gin's tama. And then after they fell off, each one was used by the clans to fight against the other one. They even got individual names.
In Yu-Gi-Oh! GX, when Dr. Crowler dueled Bonaparte, Bonaparte's monsters fire their cork-loaded shotguns at Crowler's groin. This occurs twice during the series run. Surprisingly, 4Kids kept the shots in.
Action Girl Fabiola does this to a thug during her first visit to the Yellow Flag...with a blade built into the heel of her shoe. OUCH.
Surviving this and other painful hits is what marks Rotton the Wizard as Made of Iron. More exactly, he may be a Love Freak of sorts but he was smart enough to use protection... there. Good thing, too, as he faced someone strong enough to dent said protection (namely, Roberta in full Ax-Crazy mode during the El Baile de la Muerte arc), but at least it did its job.
In episode 22 of Nekojiru Gekijo, Nyako kicks a fish in the crotch while Nyatta smacks him across the head with a plank after he hits them.
Sunmi clubs Skunk in the nuts with a microphone in Tokyo Tribe 2.
In chapters 55-56 of the Midori Days manga, Seiji enters a female wrestling competition in hopes of winning one million yen. He and another contender named "Helter Skelter" make it to the final match, but "Helter Skelter" aka his sister Rin knows his true identity and immediately begins to disarm him with repeated kicks to the crotch, prompting some rather amusing commentary from the emcee.
Emcee: "Good thing this is women! If she was a man, she'd be dead by now!"
While losing consciousness, Seiji manages to pull off a Cross Counter, knocking "Helter Skelter" out and winning the match. But while leaving the ring, "Helter Skelter" also leaves with a loose thread from Seiji's pants. Hilarity Ensues, especially when Seiji tries using his right hand to cover himself. Needless to say, he was disqualified.
Kekko Kamen inverts this trope rather humorously: instead of an attack TO the groin, Kekko Kamen's finisher, the "Open Thighs Jump," involves an attack WITH the groin, as Kekko Kamen presses her nether-regions against an enemy's face to finish them off.
A quite gruesome (but still funny) example occurs in Change 123. While fighting Hibiki, a yakuza member has his junk sliced down the middle with a katana. Hibiki is convinced to apologize to him in the hospital, but the gang member responds with threats and abuse. So Hibiki flashes him, which just makes the damage worse.
Axis Powers Hetalia: In the first episode of the World Series Canada and America play catch and one of the balls America throws hits Canada... there. Since America has Super Strength... OUCH!
One chapter has Black Star training in hand-to-hand combat with Patti Thompson. He insists that he needs to have his hands tied so as to make it a fair fight (against the girl who's beaten the rest of the class). Unfortunately, he turns around to have this done when the fight had already begun. Cue Patti gleefullykicking him in the crotch.
In the Anime, after he finds Angela and goes on a victory speech, she kicks him between his legs.
In the manga, after Dressing as the Enemy, Soul and Kid are assigned to babysit Angela. Five minutes in, she whacks Soul in the crotch with her broomstick. Finding his reaction funny, she decides to make a game out of it and does the same thing to Kidd.
In his fight against Masamune, Black Star runs circles around his foe and taunts him, but eventually slips and flies groin-first into a pole.
The manga volumes include a chapter where Lupin "teaches" a young woman to defend herself from attack by slapping her hands together on top of the... male sex symbol. (The manga's replacement for genitalia)
In episode 10 of Lupin III (Green Jacket) series, when Flinch aims a second kick at Lupin, he catches it and kicks Flinch in the crotch.
In the Lupin III (Red Jacket) series, he has used this tactic to escape from a large police officer who had him in a hold.
Attempted in the Rumiko Takahashi short film Fire Tripper; when Shukumaru takes a glance at Suzuko while she is bathing, she grabs a large rock and chucks it Shukumaru, landing inches away from his goods.
FLCL episode 6 "FLCLimax". In the manga style sequence Haruko kicks Naota in the crotch.
Pocket Monsters has a truly horrible variation. Red makes a comment about "balls" which causes Blue to check his pants, thinking he's talking about Pokeballs. He pulls his testicles, though it's in a goofy way that fits the Deranged Animation of the series (it comes out very long and stringy). This, obviously, causes Red much pain.
Played for comedy and as an actual make-shift attack in manga Blazer Drive. After finding the character known as Beast impervious to harm, main character Daichi swiftly slides his body between Beast's legs, facing up at Beast, who can only watch in terror as Daichi lifts his sneaker-clad foot and slams it, sole-first, into Beast's unfortunate groin. Beast then berates Daichi, saying that - as a hero in a shounen manga, he shouldn't be launching such dirty attacks. Daichi counters by pointing out Beast had requested he attack with everything he had, also making note of the reason for his attack's target - "That part is not hardened as well."
Rather gruesome but still rather funny: Guts of Berserkuses his sword to perform the ultimate cock-block on the Apostle Wyald as he's preparing to rape Casca. This moment of poetic justice is as satisfying as it is awesome.
In New Testament Vol. 1 of A Certain Magical Index, Touma makes a Big Damn Heroes rescue at the end when everyone thought he was dead. Once the bad guys have been defeated, he starts to explain what happened to him... when Leivinia Birdway suddenly sneaks up on him and kicks him in the groin, calling him a moron.
In one episode of Eureka Seven, Renton and a drunk Talho are making their way back to the ship when they're attacked by a gang intending on raping Talho. They are then rescued by Holland who beats up the gang and holds the leader who was on top of Talho by his nostrils. Talho then takes the opportunity to kick him in the groin as he's pulled off her.
In Ixion Saga DT, Kon is smart enough to stop Erec with a Dragon horned toe boot wearing foot to the groin. The damage is so severe the doctor was forced to remove one. Their next encounter has Kon smashing his groin this time with a ROCKET HAMMER!
In an episode of Pokémon, when Ash sends Bayleef to Professor Oak's lab, Bayleef panics and runs around, and she eventually rams into Oak's groin.
In the second episode of Xam'd: Lost Memories, a smart-mouth crewman pisses off a little kid... and the kid slugs the big jerk right in his twig and berries!
Turns up again and again in Gu-Gu Ganmo. The main character Hanpeita's sister kicks him in the crotch to wake him up every morning (one episode revolves around his attempts to get her to stop). The methods get gradually harsher as the series progresses, starting with "denki anma" (applying pressure and vibration to the groin to cause discomfort) and progressing to elbowing, stomping, and a succession of full-force kicks. Hanpeita and others fall on their crotches with some freqency, and at one point Hanpeita has a running hairdryer and a hot towel shoved down his pants in the space of two minutes. Ganmo is shown to be immune to groin attacks, but hitting his comb produces similar results.
In episode 6 of Panty & Stocking with Garterbelt, an underground explosion causes fire to spray out of all the toilets and urinals in the school, burning everybody who was using them.
In volume 2 of Air Gear, Ikki is spying pervily on Simca while she finishes her shift in the skate shop. Mikan then decides to interrupt this with a solid boot to the family jewels (and in the manga, they even make a sound like metal being hit). Predictably, he then engages in a bout of silent screaming.
In Campione!, Godou acts as a baseball catcher and takes a baseball to the groin.
Hanjuku Ninpouchou features the occasional groin kick up until Volume 5 when Miyuki begins whaling on Raita's balls seemingly every other page.
Anna from Shaman King promptly kicks the soon-to-be GOD, and gets herself quite a reputation for it.
Pictured above: One-Punch Man has Saitama accidentally hit Sonic the ninja when he tries to attack the bald protagonist with a windmill kick. Saitama's response is to hold his fist up in the direction of Sonic's groin and say "Checkmate." Unfortunately he didn't account for Sonic's momentum, leading to the poor ninja running crotch-first into Saitama's fist and Saitama apologizing. The comic cuts to Sonic sweating buckets with pinprick eyes, followed by a panel of a lovely mountain valley with the caption "Please wait a moment." Fortunately for Sonic, Saitama didn't actually punch him, because that would have been a horrible wayto go. The anime keeps the scene, in all its glory.
In Nozomu Nozomi the recently gender bent but still hiding it protagonist takes a line drive to the crotch while playing baseball and discovers that it does indeed hurt to get nailed in your girl parts and the usual techniques boys use to deal with the pain either don't work or would give away too much. It's more worrisome when Nozomu's best friend Yasu playfully mimes an "electric breaker" wrestling move (with more of a squish than an actual stomp) while they are roughhousing and notices Nozomu's crotch doesn't feel right underfoot. He almost uncovers Nozomu's secret before another teammate distracts him.
The use of the Turn A as the victim also serves as a Mythology Gag, since Turn A's protagonist Loran took a few hits to the family jewels himself, most famously jumping from one airplane to another in mid-air and landing groin-first on the fuselage.
In Yu-Gi-Oh!: Capsule Monsters, after escaping a nest of baby Duel Monsters, Jounouchi crashes into a tree growing out of the cliff groin-first.
As it's a series with Japanese Delinquents as the protagonists and most of the cast, groin attack appear rather often in Kyou Kara Ore wa!!. The most epic one was the one Mitsuhashi used to defeat a bear, without ever being told it was actually a man in a suit trying to scare him off.
In Kimi to Boku a kindergartener once kicked Kaname in the groin.
Tsukamoto from DAYS gets hit in the crotch with a soccer ball in episode 1.
Yukari Sahashi starts developing a habit for it in Sekirei. She's helping Shiina, the Sekirei she winged, find his "sister", Kusano,note She'd long found her Ashikabi in Yukari's older brother, Minato, but she doesn't know this. but she kept running into misbehaving young men instead, which she promptly dispatched with the trope, earning her the moniker "Demon Ashikabi".
Momo of Peach Girl does this to Kairi's brother Ryo when he tries to rape her.
Episode 12 of Macross Frontier has Alto finishing off the rebel leader by stabbing his Powered Armor's groin with a knife. One could only wonder how much damage a knife that can penetrate power armor causes to organic tissue... Especially since both combatants are the size of mechas and the knife is sized accordingly.
In one episode of Yu-Gi-Oh! ZEXAL Yuma did this to Gauche when he and Droite tried to use muscle to interrogate him after Haruto was kidnapped. (This time the dub edited it out, probably because, unlike the case in Yu-Gi-Oh! GX it was not supposed to be funny.)
Used in Video Girl Ai, when Youta puts on a Jerk Ass Facade and assaults Ai to save her from Rolex's control. She reacts buy squeezing his nuts until the pain makes him stop, and then she realizes what he was truly trying to do.
Present in Airmaster during the combat betwheen Minaguchi Yuki and Aikawa Maki.
Hiro in Ginga Densetsu Weed has a nickname called the "ball-snatcher." It REALLY involves tearing off the privates of other dogs. Truth is, he was training in that to take down Kamikiri, who killed his father when he was young.
No. 6: Sion does this to a greasy old corpse collector in chapter 6 that was hitting on him and had bad intentions towards him.
In Eden No Hana, Midori applies one on her rapist stepbrother to escape from him and join her real brother, Tokio.
In Soul Eater, Death the Kid seemed to have no qualms about kicking Mosquito-from-200-years-ago between the legs during his fight in Baba Yaga's castle.
In Anatolia Story, this happened to Urhi in the past. He's an eunuch, and hides this fact until people accuse him of being Prince Juda's real father, which technically is impossible since he was castrated before he met Jude's mother Queen Nakia.
In Berserk: The Golden Age Arc II - The Egg Of The King, Guts thrusts a guard in the groin with his sword while fighting his way out of Count Julius' mansion.
Being a manga on Professional Wrestling (even if they treat it as real), Tiger Mask features them with a certain frequency. And the second-to-last story arc establishes that the tournament is filled with extremely capable heels when two of them react to a rather vicious one (it involved a chain and breaking the victim's groin cup) by calling it childish (Tiger Mask, who executed it, privately agreed).
Cynthia the Mission had this done to a girl. With a TOE BLADE. Kanae pops a blade out of her shoe and kicks Bridget in the crotch, and as Bridget was wearing a short pleated skirt, all that was between her vulva and the weapon was her panties, which the blade sliced through easily, plunging into Bridget's underparts, presumably into her vagina. Though not directly killed by this devastating blow, Bridget is, unsurprisingly, heavily incapacitated by it, and tries to stagger away, bleeding severely from her crotch.
Poor Inui in Shinjuku D×D. He gets one when a Yakuza decided to shove his gun in his crotch (thankfully he didn't discharge the gun), and another one from a different member of another Yakuza group with a taser.
The backstory of Juuzou Suzuya reveals that he's so androgynous because his "Mama" castrated him with a hammer to prevent puberty.
In a blink-and-you-miss-it moment, Shuu Tsukiyama's wanted poster mentions that he murdered and castrated a politician.
The sequel features the female Ghoul Ayu, nicknamed "Nutcracker" for her preference for stomping on men's genitals and slurping them up like oysters. One unfortunate Red Shirt suffers this fate, while Shirazu barely escapes with his goods intact.
Mutsuki does this to Takizawa, kneeing him and following it up stomping on his genitals. It's not only dirty fighting at its worst, but an early indicator of the trouble to come.
Played for both Drama and pitch black comedy in Thou Shalt Not Die where the group is coming under fire from a sniper. The first shot ends up costing Botan her hand, the second ends up hitting Mizukaki in the nether regions. What makes it comedy is the face he makes as it happens.
A blink and it's missed moment towards the end of the Another anime features the trope: Yumi slips when she tries to stab Mei while leaning onto a slippery window ledge, only to land crotch first on said window sill... and then to end up fallingto her own death.
Lakshi from Kaze No Tairiku pulls off a nut shot that catches her attacker in mid-air.
In Dragon Ball Super, after upgrading his sword into a Laser Blade powered by the combined ki of everyone on the planet, Future Trunks splits Merged Zemasu in half vertically, starting at his groin. And he holds his sword there for several seconds before moving it up.
Dog Soldier: Hiba cuts the member off of an attempted rapist.
Dokuro: Takeo rips the penis off of a prisoner who plans to rape him.
In Captain Tsubasa Rising Sun, it's revealed that Juan Díaz's reason to not have attended the World Youth Cup was this trope. During the Argentinian championship, he got kicked so violently near the crotch that his hip bone and cartilages were damaged so he had to be operated on and then hospitalized for several months, causing him to miss the WYC. He recovered well enough in the end, however.