Excel♥Saga substituted scenes of sunsets and seashores for footage of bloody violence in "The Koshi Rikdo Assassination Plot" — but didn't change the soundtrack, so you got to hear everything that happened. A similar gag occurs in "Take Back Love!", where random pictures of Puchuus are used to cover up the visuals (but not the sounds) of a non-consensual lesbian sex scene. Conversely, in "Butt Out, Youth", peaceful music is used to cover the horrible sound of Excel dragging metal claws across a blackboard.
One version of the Puni Puni Poemitrailer (available here) opened with a short message that they removed anything offensive to anyone so that it could reach "the widest possible audience". The result? A black screen. Remove anything offensive to "most people"? Another black screen. Remove "anything that might get us sued"? We finally get the trailer, with black screens with funny text replacing some scenes. This entire affair is made very funny when you remember that this version appeared on a Milk-chan DVD! The uncensored version, by the way, is available here.
In episode 16 of Gakuen Alice, a bumper screen comes up with the giant Piyo and the stuffed bear. The bear holds a sign which simply says, "Please wait for a moment." ("Shibaraku omachi kudasai.") in place of the violence Mikan undoubtedly intends to visit upon Natsume.
In episode 30 of Keroro Gunsou, it cuts away from Giroro being stretched in a body-sculpting aid/medieval torture device to cute, fanservicey shots of Natsumi. The equivalent chapter of the manga has the same gag, but instead censors it with a single panel full of nothing but speech bubbles and painful-sounding onomatopoeia.
In chapter 50 of the manga, during a black-out in the base, Giroro beats the crap out of Keroro for squandering their invasion budget and, at one point, hits him with "an attackno mangacan express!"
In addition to having a small cartoon man with a sign censor minor infractions, Hayate the Combat Butler also uses Relax-O-Vision during particularly egregious acts of senseless violence, mostly involving replacing the visuals with a landscape or façade shot of the area/building, or by mild fanservice. The audio isn't affected, however, making it abundantly clear what's going on.
Almost always, it is a picture of Hinagiku that is used as Relax-O-Vision.
Subverted in the manga, when one of Hayate's vicious smackdowns of Gilbert is covered by... er, scenes of senseless violence.
Azumanga Daioh: Nyamo's drunken sex ed lesson is overlaid with relaxing music and uplifting visuals, such as windchimes, a paper lamp, and the earth with the sun rising in the north, occasionally cutting to the students' embarrassed enthralled faces. An Eye Catch featuring Chiyo and Tadakichi is used as a Vomit Discretion Shot earlier in the series when a drunken Yukari pukes in the street.
A somewhat literal and more serious usage of this trope occurs in Gundam Wing, when Treize broadcasts images of a peaceful, sunlit field to Lady Une's Leo while encouraging her to calm down.
"Nice Boat." A real-life example: The violent anime School Days is infamous for being taken off air due to a recent violent murder, and being replaced by a half-hour long clip of a boat peacefully floating on water. This one gets bonus points because the last episode actually does end with a boat sailing serenely on the ocean. The passengers however are anything but.
This is not an uncommon way for Japanese television censorship (voluntary or no) to take place, which is why there are so many manga/anime examples. When used inside a story for some truly nefarious/egregious censorship, though, it can be pretty creepy (e.g. in Neon Genesis Evangelion, there are several layers of secrets regarding the Evas and Angels; since it isn't really permitted for the general public to know much about them at all, TV broadcast kicks on the Relax-O-Vision in one episode, which makes military nerd and borderline conspiracy theorist Keisuke suspicious).
Done in the Persona 3 manga in an omake. Minato is playing a rail simulator, and sets the speed to "Excessively powered mach speed" to the point where the rails started to melt from the friction. It shows Junpei's horrified face with the caption "Please enjoy Junpei's expression in place of the graphic scene on-screen" with horrible bold sound effects.
This is used in Yu-Gi-Oh! whenever one character punches another, having the characters out of frame, both in the original footage and the dub. However, it only occurs once or twice in the original, and numerous other times punches are shown on-screen with no cutaways (these on-screen punches are, of course, cut out of the dub), so the couple of occasions where they do use Relax-O-Vision are rather out of place.
In an odd case of Values Dissonance, 4Kids DIDN'T decide to censor the scene during the Battle City Finale when Obelisk The Tormentor punches Yami Marik during a Shadow Game, despite the fact that Obelisk's fist was the size of Marik's ENTIRE BODY and (since the Shadow Game makes the creatures physical, rather than holograms) sends him flying several feet backwards, ending up with him sprawling on the ground.
In Bludgeoning Angel Dokuro-chan, the non-DVD versions have a rather...calming photo of a beach in place of Dokuro-chan and her sister respectively molesting (read: washing the back) the protagonist.
In an episode of Ranma One Half, particularly severe beatings are replaced by (animated) footage of heavy construction machinery in operation. Subtle.
Suffice to say, that scene was used in the abridged series with the sounds of a vicious beating playing while showing the "not-very-subtle symbolism," a-la the first Excel♥Saga example. The pile-driver was a beautiful touch.
Does this really count? It only happened once, and the silent shot of some pile-driving equipment was used to cover the fact that Akane had just given Ranma-chan and Ryoga each a single powerful slap on the face for shearing off her hair.
Used in Mahou Sensei Negima! when Negi, possessed by the magic of The World Tree in the Mahora Festival arc, gives Asuna a very passionate kiss. Just as it's implied that Negi starts to slip a little tongue in, we cut to a peaceful sea-side view with a cute turtle (Tama from Love Hina) in the foreground. "Everybody please wait for a while. Talk for a while".
Used during episode 6 of the K-On anime, when Mio trips over a microphone cable and gives the entire auditorium a very clear view of her striped blue-and-white panties. This is shown in the 4-koma, but in the anime, the scene cuts away to a blue-and-white striped bowl of rice. Also, almost everytime Mio hits Ritsu, it cuts to a closeup of something else in the room, and then back to Ritsu, now with a Cranial Eruption.
In the fourth episode of Princess Lover, there is a brief picture of a mountain as Seika beats Haruhiko into the wall.
Ep.7 of To Love-Ru has a fight between Ren and a mountain ape interrupted by Haruna showering. He gets into another fight later in the episode, which is again interrupted by shower scenes.
In the YuYu Hakusho manga, at the conclusion of the Sacred Beasts arc, Kuwabara tricks Yusuke into thinking that Keiko and Botan were killed by the zombies that attacked them. Upon learning that they're really safe (though not before freaking out), Yusuke is implied to give Kuwabara a savage beating (even for him) for his twisted little joke, while the panel cuts to a picture of a kitten and the caption "We'll hold for a while as Kuwabara gets his head handed to him".
In an episode of Axis Powers Hetalia, America asks France for diet tips. Then, a white screen pops up explaining that France's response is "educationally inappropriate" or something like that, so they'll be cutting out that section. France is pissed.
There is also a sequence set during the WWII storyline where Japan attacks China. Readers are treated to a panel featuring a panda while China's cries of anguish are heard in the background.
Happens in an episode of Galaxy Angel in which Vanilla discovers she has a secret admirer. During the course of said episode, the rest of the Angels ask her different questions, such as if she knows what a love letter or a romantic relationship are (justified since Vanilla is also an Emotionless Girl), and every time she replies the camera does a close up on her moving lips (without sound) before changing into a picture of a different landscape each time. Then, we're cut back to the other Angels (minus Milfeulle) blushing in embarrassment.
Appears early on in The Wallflower anime, where, e-hem, certain scenes are replaced with a picture of a pretty flower on a meadow. As the sounds in the background get more and more gruesome, the flower starts spinning.
In Great Teacher Onizuka, shortly after fantasizing about Onizuka and herself on a beach, Fuyutsuki runs to the bathroom in her coworker's house and jumps in the tub. The viewers are treated to a black screen with flashing, scrolling text that says something like "For certain reasons, we cannot show the image".
SHUFFLE! has Sia beating up her father with a chair on occasion. One time when she was particularly pissed off, it switched to a message of apology for not showing the scene.
In one of the Haiyore! Nyarko-san shorts, Nyarko and Mahiro do the Disney Dog Fight over her pet Shantak...who immediately chooses Mahiro. Nyarko flips out and we get a censor screen by the Space Police over the sounds of violence; when we cut back, Nyarko is panting for breath while snuggling a badly beaten Shantak and cooing about how she's such a good pet for "choosing" her mistress.
A slight variation was seen in a sketch on The Whitest Kids U Know, when Trevor and Timmy Break The Fourth Wall by explaining that they couldn't think of the ending to the sketch and instead have a girl take off her top and bounce around "to help DVD sales" because her exposed breasts are censored on television but would be uncensored on the DVD.
In a few Astérix books, particularly violent brawls only happen off-panel. In Asterix in Belgium our heroes get in a fight with Romans, which is hidden by a flowery curtain pulled over the panel (as seen above).
Suske en Wiske employs the same flowery curtain when Jethro becomes particularly violent (since Jethro using enemies as melee weapons does show up, one does wonder what's behind this curtain...)
In one such instance, it is mentioned how Jethro expertly makes use of a technique called "furniture swinging."
Occasionally used in the British Anthology ComicThe Beano. Calamity James often employed it to obscure some particularly painful misfortune inflicted on the hapless James.
Non-animated variation: In the Tarantino/Rodriguez double feature Grindhouse, both movies ("Planet Terror" and "Death Proof") feature "missing reels" to give them an authentic, old-fashioned feel. However, both missing reels are inserted during apparent sex scenes; given the rest of the content of the movie, it's obviously not really done for censorship purposes so much as purely for the gag. In fact, Planet Terror's missing reel covers up a fairly major plot revelation, and comes just toward the end of the sex scene. As the film leads up to the sex scene, it gets more and more heavily scratched until the missing reel, the implication being that the sex scene was played so many times that it fell apart. Tarantino got the idea for "missing reels" after he watched a B-movie that skipped over a plot point due to a missing reel and realized that you could interpret the rest of the movie differently depending on what had happened in the missing footage.
This is also a not so subtle nod to the fact that missing reels containing sex scenes were common in "Grindhouse" theaters because the projectionists would steal them for personal use.
This happens more due to the lack of budget and no post-production than actual Relax-O-Vision in Dogma, in a part cut from a scene, where Azrael shows Bethany exactly what hell's like now that human imagination has made it even worse. A title card is then flashed on the screen: [ten seconds of the most fucked-up imagery to ever be shown in cinema] before cutting back to Azrael hissing, "I'd rather die than go back to that."
George of the Jungle does this several times. When an extra falls off a bridge suspended several hundred metres over a canyon or George is shot by the Big Bad the narrator quickly interjects with the line, "Whew! Let's all calm down, now. Don't worry, kids, nobody dies in this film, they just get really big boo-boos," before moving to the next scene showing the victim covered in dozens of bandages and casts.
Another live-action version in The Princess Bride...she does not get eaten by eels at this time.
Used mercifully during the Room 101 scene of the 1984 movie.
Used by WNN in Cloudy with a Chance of Meatballs. Head anchor Patrick cuts from Sam reporting on the spaghetti twister to a shot of a playful puppy over scrolling weather forcasts, not due to any technical difficulties, but due to her recently reembraced nerd style.
"We'll get right back to that storm, and hopefully Sam will look a little more appealing."
One of the video trailers for Braindead had, for the sake of viewers of a nervous disposition, scenes from the film only on the right side of the screen, on the other side were some pictures of lambs. However, right at the end, one particularly gory moment does fill the whole screen. This can be seen here
In Astérix: Mission Cleopatra, a voiceover announces that due to the violence of the few next scenes, a short documentary on crayfish will be shown instead. After that, the view cuts to Roman soldiers flying all over, with very audible punch sounds.
Another live action example with the sound intact; according to IMDb, the original Japanese cut of Dawn of the Dead had the film freezing on the frame prior to any gore scene, with the sound playing through, and having the film jump back into motion once the offending moment passed.
Played with in the British film Cuts, about a man trying to write a screenplay. Early in the film, a man in the film industry makes a very loud joke that in his day, to refer to sex, you would show a field of waving corn, while today, to refer to a field of waving corn, you show two people having sex. Suffice to say that both versions happen in the film.
In Brazil the protagonist Sam Lowry appears to pull off a last minute escape from torture and is reunited with the love of his life. In the last moments of the film it is revealed that Sam actually experienced a psychological break.
In The Adventures of Tom Sawyer, Tom has just successfully conned all his friends into giving him enough tickets to receive a special prize in Sunday School for Bible memorization. However, he didn't count on his surprised teachers proudly asking him to display his Scripture knowledge by answering a few questions. Needless to say, his cover is blown when when he answers the question, "Who were the first two disciples?", with, "David and Goliath!" At which point the narrator interjects: "Let us draw the curtain of charity over the rest of the scene." End of chapter.
In The Bartimaeus Trilogy, this is done in The Amulet of Samarkand when Bartimaeus interrogates an imp. All we know is that afterwords Bartimaeus is slightly sweaty and the imp is a model of cooperation.
Used in-universe in The Restaurant at the End of the Universe with the Peril-Sensitive Sunglasses. "Especially designed to help people develop a relaxed attitude to danger. They work by turning completely dark at the first sign of danger, thus preventing you from seeing anything that might alarm you."
Live Action TV
On Monty Python's Flying Circus, a sketch involving a four-star restaurant in the middle of the jungle cuts out just as bushmen are about to attack the diners. A faux BBC apology plays over the scene, with the announcer describing in rather graphic detail the violence and nudity that will not be shown. In typical Python fashion, they play the 1958 Gardening Club instead...and a few seconds into footage of a formal garden, in run several nude women, the Pantomime Goose, Mister Gumby, and others having a frantic, clumsy orgy.
A variation occurs in another episode. Following the ridiculously violent "Sam Peckinpah's Salad Days" sketch, and the subsequent gunning down of critic Philip Jenkinson in slow motion, the show ends with several minutes of waves crashing against the shore.
Top Gear: Split-Screen Optional. Not censorship, rather an anti-boredom device:
Clarkson: Now I'm going to talk about all the German technical stuff but for those not interested in all that, on the left-hand half of the screen we'll be showing kittens!
Happens a lot on Everybody Hates Chris. Usually it is just when Chris is about to do something bad. One example was when Chris was handed a bag of marijuana by a criminal trying to escape the police. His friend Greg suggest they smoke it. A screen then comes up and says that Chris Rock does not endorse the smoking of pot. He instead decides to put it in lasagna.
A segment on the German The Daily Show style "heute-show" that has correspondent Gernot Hassknecht ("Hateservant") peacefully commenting on a news story, then launching into a hateful tirade. After a few seconds he is cut off by a VHS recording of the network's 60s-era Technical Difficulties screen with elevator music in the background.
Parodied in the "Kim Jong-Il Show" sketch on MADtv, where, when censoring JC Chasez's musical number, threatens to cut the song to kittens when it gets too sexy, which he does.
On one episode of How I Met Your Mother, the gang and Victoria (Ted's girlfriend at the time) recount the most embarrassing thing that ever happened to them. Victoria starts to tell her story, then they cut to an all-black screen. Future Ted's voiceover says "Kids, I know I tell you a lot of off-color stories, but there's no way in hell I'm telling you this one."
In a Liberty Meadows strip, the "graphic and nonpolitically correct" panels have been replaced by a picture of a bunny, who says: "Gosh, I'm so cute and nonthreatening."
Liberty Meadows has invoked this several times. One time, there was a mundane one-panel comic "Yard Apes" ("I'm e-mailing Grandma a hug.") drawn as being taped over an implicitly fanservicey image.
Also done in My Cage with the Censor Sheep standing in for regular strips pulled for controversial/offensive content. Also done with bunnies in The New Adventures Of Queen Victoria - all of which are homages to Walt Kelly, who had "cute bunny" strips on the ready for newspapers too nervous to run regular strips of his (often controversial and outspoken) Pogo.
In a Garfieldstrip◊, Jon says to Garfield: "If you beg, I'll let you lick my ice cream cone." In the next panel, there's a title card saying: "The cartoonist has elected not to show this panel due to its graphic nature."
After a character is angered to the point where it looks like he's about to blow, a Bloom County strip covers up the following panel with a title card reading, "A scene of unimaginable violence."
Happens in a couple of Yenny strips in spring 2006, whenever the title character's pet lizard does something bad.
At least one Krazy Kat strip censors the usual "Ignatz beans Krazy with brick" gag thus:
The original radio version of The Hitchhikers Guide To The Galaxy included an interlude during the approach to Magrathea where, supposedly in order to help combat rising stress levels in the galaxy, it was carefully explained to the audience that no one was going to get killed in the ensuing confusion — although one unidentified person would be bruised on the arm. The novelization did this too, as did the television series, the latter of which used posterization and other special effects to obscure the action as the Book explained what was going on. The LP of the radio series includes a twist; listeners who allowed the album to play into the spiral scratch at the end would hear a short audio outtake informing them that it was Arthur whose upper arm was bruised.
The same series, of course, includes the famous Peril Sensitive Sunglasses, which help you take a relaxed attitude to danger by going black at the first hint of trouble to prevent your seeing anything that might alarm you. A pair of these glasses were provided as feelies with the text adventure game. They're totally made out of black cardboard.
The special ability "Devour" in Final Fantasy VIII cut to a scene of a peaceful meadow with a disclaimer about sensibilities, rather than show the character consume the monster. When the move is successful, a sound bite of something gruesome happening out of sight played.
Selphie' Limit Break "The End" worked with similar visuals; Memetic Mutation by the fans then turned Selphie into a Reality Warper capable of "wishing people into the cornfield".
There is a Double Subversion in Dragon Quest VIII. One of the secret places is a sort of brothel, where you can get a "Puff-puff" from one of the girls. There is a black screen, because the character is blindfolded, and we hears sounds of something squishy, but then the screen brightens up, and we just see the girl squishing a couple of slime dolls against the character's head.
As a general rule, you should never trust a strange woman offering "Puff-Puff", as this sort of thing happens in more than one Dragon Quest game, and the result is never pleasant. In Dragon Quest III, the Puff-Puff is administered not by the girl who drags you to her house, but by the girl's extremely manly father, and in Dragon Quest IX, the girl uses a pair of sheeps' butts.
The Super Move of Morrigan Aensland in the Darkstalkers series. If it connects, red curtains close over the screen for a few seconds, during which silhouettes provide a vague idea of what she's doing to her opponent. Never mind the fact that she's a succubus...
In Space Quest 3, if you don't get off the garbage conveyor in time, "NOT A PRETTY SIGHT" covers the disposal unit as Roger is shredded. Rather than relaxing the player, it actually serves to make this way of dying funny.
Playing Katawa Shoujo with sex scenes turned off brings in pictures of stuff to replace them. (For instance a sex scene in Shizune's route is replaced by a picture of cantaloupes.)
In Runescape, there's one quest where you need to find a brain surgeon to fix a bunch of monks after their brains were swapped out for zombies (long story). After you find the doctor in question, get him to the monks, get the supplies, etc, etc, he finally starts the surgery. Before he starts, he asks your Player Character to record what he does, for posterity. The scene cuts away to a graphic of a cat playing with a ball of yarn. When the scene comes back...
Player Character: I DON'T WANT MY EYES ANYMORE!
Meta-example in Valve's "Meet The Pyro" short film for Team Fortress 2. The implication is that the Pyro's perception of the entire world consists of Relax-o-Vision - with rainbows, lollipops, dancing unicorns, chibified "baby" Blue Team members, all set to the tune of "Do You Believe In Magic."
Edna & Harvey: Harvey’s New Eyes reflects Lilli's inability to comprehend death by covering dead bodies in pink paint, applied by little potato-shaped gnomes that only she can see. It's generally a thin enough layer to get a good idea of what's just happened, but she never has an option to interact directly with it, and displays absolutely no curiosity about it. (The paint stops appearing later on in the game when the protagonist's illusions begin to break.)
Interestingly, no character in the entire game displays the ability to recognize a dead body—it's just that the others convince themselves the dead are still alive, whereas Lilli can't see them at all. Mother Superior even gives an award to a girl who's hung herself out of despair.
Killer Is Dead Bryan's about to get hit by a train! Cut to a Unicorn in a grassy field while "Please Stand By" marquees across the screen. Cut back to Mikacatching his robot remains and Mondo swearing his death won't be in vain.
Whenever sex is meant to be portrayed on Girly, the panel instead shows a scene with the characters involved dancing with happy mammals in a world where everything has an incredibly cute face and sings "Lalalala". It was even done in thought bubbles! Example here.
Taken a step further when she censored the visual part of a fight that ended in the death of Fat Chocobo in this animated strip. Dialogue and sound effects are still visible, though ironically, the former is uncensored (ie: early on, Porom says "Kick his ass!").
Flintlocke's Guide to Azeroth has this one here when Flintlocke is using Beaverstick (don't ask) to fight against an Everblooming. Naturally, the character protest immediately that they want to see the fight.
Nodwick at one point features a panel explaining that Nodwick's brain turning into coleslaw followed by his head exploding couldn't be shown, so it cuts straight to the aftermath.
The Suburban Jungle usually covers up fight/predation scenes with a text banner announcing "A scene of indescribable carnage" or words to that effect. 
Weaponized in-universe in El Goonish Shive by the immortal known only as Jerry. He has a spell that causes the target to suddenly perceive itself as being in a grassy field surrounded by adorable fluffy animals. It's only been used once so far, but when it was, it reduced a character from an angst-driven rampage to vaguely River Tam-like babbling in seconds.
GG-Guys had Dave wear Relax-O-Vision goggles to portray the censored version of Left 4 Dead 2. It did not end well.
Subverted in Errant Story, where Meji's early melee with the guards at the Heretic Knowledge Vault (using her familiar Ellis as a melee weapon) goes on behind a relax-o-vision curtain. However, that wasn't out of concern for the sensibilities of the reader; it was because Poe was too lazy to draw the melee scene. (He said so.)
In a part of Homestuck, the view is changed to a dead person (killed earlier by one of the characters) while someone gets beaten up in a jail cell. It is used twotimes, in quick succession - and subverted the first time, because it cuts back too early!
In Jalyss Dislikes Headcrabs, Jalyss shows pictures of puppies while describing how a headcrab attaches itself to a victim because there is no way she's showing anything that disturbing.
This happens in Four Swords Misadventures while Red Link is being pummeled by the Cuccos during Episode 4. The screen even displays the words "Relax-O-Vision" superimposed on a field of flowers with a blurb about the scene being unsuitable for those with weak stomachs, perhaps as a Shout Out to the original Freakazoid "Relax-O-Vision".
In another possible example, Green Link and Red Link are fighting each other, and then the scene cuts to Blue and Purple in a theater, watching a parody of the infamous ant speech from Naruto. When Blue and Purple get back to where the fight was, it's already over.
This◊ image macro: "Calm the fuck down. Look at these kittens."
In The Grim Adventures of Billy & Mandy episode "Here There Be Dwarves", R. Lee Ermey, of all people, pops up to explain that a fierce battle between dwarves and elves is too gruesome to show to younger viewers, so they will be showing a clip of a cute koala instead. However, they accidentally cut back briefly to the battle before the carnage is over, and Ermey remarks "That was entirely my bad! I misread the signal. I knew a guy named Joe. He misread the signals in a combat situation - now he eats everything through a mechanical straw!"
Parodied in thisYoutube Poop. (Begins at 2:20. Warning: one of the clips shows a monkey's brain).
In the Courage the Cowardly Dog episode "The Magic Tree of Nowhere", this happens after Courage climbs into a hive. The camera pans across a beautiful field while only Courage's screams of pain can be heard in the background.
In the Drawn Together episode "Alzheimer's That Ends Well", Wooldoor covers Clara's genitalia with himself, explaining that they cannot show it because of the FCC. When he proceeds to explain what FCC stands for, his mouth is pixelated and his words are beeped out.
Aqua Teen Hunger Force episode "Gee Whiz". Pretty much the entire episode is a parody of this trope combined with religious censorship.
Variation from Dave the Barbarian: "And so our heroes defeat the muffin in an exciting battle, which we can't show you because it would be much too expensive for a cheap show like this."
Played straight in the episode where Chuckles takes over the show by enslaving the narrator. He writes a scene where he defeats Dave and his family, but the narrator can't read it because it's "far too violent for a family show". Chuckles makes some adjustments and hands the script back. The narrator okays it, and they cut to the exterior of the castle, as it bounces like crazy and a fierce battle is heard; the narrator's dialogue is somewhere along the lines of "And lo, the Dark Lord Chuckles the Silly Piggy does inflict many vague but presumably unpleasant things on the smelly barbarians."
South Park's portrayal of Mohammed ordering food at a stand was censored by Comedy Central. After much kerfuffle, Comedy Central replaced it with Relax-O-Vision, allowing Matt and Trey to describe the scene and express their feelings about the censorship. (Oddly enough, South Park had showed Mohammed previously without having censorship problems.)
The daytime broadcasts of the episode "Red Hot Catholic Love" cut to Relax-o-Vision during scenes where the characters crap out of their mouths. A black screen with text describing the censorship, accompanied by a few seconds of soothing music (and then the sound of them actually doing it). The late-night version is not censored.
The theme song to the Earthworm Jim cartoon includes a cut away from Peter Puppy-monster induced ultraviolence to Jim in a hammock accidentally swallowing a butterfly to relaxing music, and then back to the aftermath of said violence.
Freakazoid! is the Trope Namer. This results in Freakazoid charging to fight three of his most notable villains, then Relax-O-Vision kicks in and when it goes back to the show, Freakazoid is standing over his defeated enemies and says "Wow! We must have blown the entire animation budget on that one fight!" Freakazoid finally loses patience with this after the Relax-O-Vision interrupts him kissing his just-rescued girlfriend, and confronts the Relax-O-Vision creator. Just as Freakazoid is about to start pummeling him, the Relax-O-Vision kicks in once again - but, this time, the sound effects of a fight are audible over the "relaxing music".
Variation: in a Tex AveryScrewy Squirrel cartoon the squirrel is chased by the dog into a pitch-black cave where loud violent noises rage. Squirrel steps out into the light, telling us "Sure was a great gag, folks - too bad you couldn't see it!"
The Bugs Bunny cartoon Rabbit Punch ends with Bugs Bunny about to be run over by a train. As the train barrels toward Bugs, the film breaks. Bugs walks onto a blank screen and announces, "Ladies and gentlemen, due to circumstances beyond our control, we are unable to finish this picture. And, uh, confidentially," he adds, holding up a pair of scissors, "the film didn't exactly break."
Similar ending to the Daffy Duck cartoon My Favorite Duck, where the film breaks while Porky Pig is chasing Daffy Duck with a gun. Daffy then describes the missing action where he fights back against Porky and gains the upper hand, until Porky hits him over the head with his rifle.
Another Daffy Duck cartoon from 1938 called Porky and Daffy has someone pull down a shade that says "censored" before a big fight.
Oggy and the Cockroaches does this frequently, even having the characters either move the camera, or put a picture in front of the camera to stop us from seeing the ensuing violence. They do show the result of the violence, though.
Spoofed in the Merrie Melodies short "Cross Country Detours". At one point, the screen splits to show a snarling Gila monster on one side and a cute little girl reciting a nursery rhyme on the other, for those who might find the Gila monster too scary. Eventually, the girl shouts at the Gila monster to shut up, scaring it away.
Spliced: To avoid damage to young minds, we've been ordered to replace this fight scene with happy puppies