Countless times in Slayers, when someone wastes a perfectly good spell by shouting something to the effect of "You forgot about me!".
In Dragon Ball, this trope preserves Son Goku's status as The Hero. His much weaker best friend Krillin has a signature attack, the Kienzan, that can cut through absolutely anything, including the most powerful enemies...so long as it actually hits them. This should mean that Krillin can take out anybody in the series (well, almost anybody), with Goku needing to do no more than provide a distraction. The problem is, Krillin feels compelled, even when trying to launch an ambush (the only way he has much chance of hitting the bad guys who are invariably much stronger and faster than him), to scream "KIENZAN!" at the top of his lungs. Thus, he never accomplishes more than slicing off an alien's tail in Dragon Ball Z, allowing Goku to be The Hero.
One Piece hero Monkey D Luffy is the epitome of this trope. Subtle is not in his vocabulary so when his crew suggests something like sneaking around, Luffy's go-to action is "Scream at the top of your lungs and punch the shit out of anyone standing in your way".
During Ace's cover story, when trying to infiltrate The Marine G2 base, he winds up blowing his cover by punching out a Marine who talked smack about Whitebeard.
And then there's Zeo's attempt to sneak up on Brook using camouflage, which fails due to him calling his attack. Cue Zeo getting rewarded with a nice taste of Brook's sword.
Perhaps the earliest example is Luffy and Usopp eavesdropping on Kuro and Jango plotting to kill Kaya. Luffy's first reaction is to jump up into plain sight and yell "HEY YOU JERKS, DON'T KILL KAYA!"
Fate's pretty little skull in Magical Girl Lyrical Nanoha would have been sporting a nice, big fracture had Nanoha not screamed "Take this!" when attempting to bash Fate's head in from above during their final battle in the first season. Moresilentattempts by others have been more successful, and Nanoha herself gets better at it once she's not nine years old anymore.
Mobile Suit Gundam SEED has a sneak attack from behind by a suit that can turn invisible. And then the pilot not only yells, but more importantly turns off its stealth and (accidentally) jumps onto its target's sword. Poor Nicol not only dies, but crosses into Too Dumb to Live territory with this stunt.
Black Star, of Soul Eater, would be the greatest ninja ever known if he could prevent himself from screaming at his potential targets as he approaches and/or proclaiming his awesomeness mid-fight.
Demonstrated beautifully in his debut which opens with Black Star calmly stating some assassination strategies, immediately followed by him leaping right in front of his targets and shouting "I am here to assassinate you!". His partner Tsubaki's reaction says it all.
The protagonists of Psyren at one time need to stealthily infiltrate a top secret installation. What course of action do they take? Blast through the ceiling.
In Flight 714, Spalding has all the passengers of the hijacked flight at gunpoint except Tintin, who is sneaking up behind him. Carreidas takes notice of this, and calls on Tintin to surprise Spalding and take his gun, causing Spalding to turn around just in time to prevent this from happening.
In one issue of The Punisher a bad guy loudly announced his intention to attack Frank from behind. Frank, of course, lampshaded it and blew his brains out. At once.
In Revenge of the Sith, Obi-Wan Kenobi has to kill General Grievous. He manages to sneak up behind him unnoticed, and of course he cuts his head off, right? Wrong, he says "Hello there," drawing the attention of an army of droids and Grievous himself. In fairness he was serving as a distraction so that his reinforcements could arrive and he wouldn't have to fight the army by himself.
In Repo! The Genetic Opera, Graverobber is trying to silently rob graves - which would've gone really well if he hadn't belted "And it's my job... to steal and rob... GRAAAAAAAAAAAAAAAAAAAAAAAAAAAVES!" halfway through his song. Hilarity Ensues, possibly Crowning Moment of Funny, at least because of Shilo's face.
In Judge Dredd, during the sentencing, the Block Overlord attempts to shoot Dredd when his back is turned only to give away his ambush with his battle cry.
Block Overlord: Let me guess: Life. [draws gun] Yaaaaahh!!
Judge Dredd: [turns around and shoots] Death. Court's adjourned.
In Jay and Silent Bob Strike Back, the thieves manage to get past the various anti-theft devices protecting a priceless jewel...until one of them lets out a gut-busting fart and triggers a noise-alarm.
In the Fantastic Four sequel, they decide that the only way to get the Silver Surfer's board back from Dr. Doom is to use The Human Torch's new "powers" to combine all their abilities to allow him to fly, but also be as strong as The Thing, and be invisible so he can sneak up on Doom. It works perfectly and he gets to within 2 feet of Doom. But rather than just knock him out, he has to say "To quote a friend, It's clobbering time." thus blowing the cover and starting a drawn out battle... all while the Earth is about to be destroyed. Great priorities there.
For super-heroes, it's not about punching the bad guy, but also delivering a snappy one-liner while you do it. Far cooler.
In Back to the Future, the Libyans decide they need to turn their lights on just as they are approaching the mall parking lot, allowing Doc to see them coming, but subverted in that even with this it doesn't give Doc enough time to escape. Even stranger, they had their lights on when they passed Marty and Red so they chose to turn their lights off some time in between, but then turned them on at pretty much the exact time when they would have wanted to have them off.
In Hot Shots! Part Deux, there is a scene where Topper Harley is trying to stealthily recover a set of keys from a sleeping guard, and reaches through the window of the shack with a broom handle. He ends up knocking over a pepper shaker, smacking several other objects, jamming the broom in the guard's ear, nose, and eye, then activates a radio loudly playing the Star Spangled banner (and hastily switches it off) and then shoves the handle into a table fan that proceeds to chew up the handle like a circular saw. The guard sleeps through the whole thing, until a mouse comes along and sneezes quietly (because it sniffes the pepper from the aforementioned pepper shaker).
At the end of Batman: The Movie, Batman proposes he and Robin leave the top floor office of a skyscraper "inconspicuously... through the window" and they proceed to climb slowly down the side of the mammoth building in broad daylight as the credits roll.
Film - Animated
In Shrek 2, Shrek and Donkey are listening in on Prince Charming, the Fairy Godmother and King Harold through a window. At one point, Charming says "Oh, thank you mother." This prompts Donkey to blurt out "Mother?!" which promptly gives them away.
In The Emperor's New Groove, Kronk sneaks out the palace with the unconscious Kuzco in a sack, humming his own dramatic theme music as he goes. At one point he hides against a wall, holding the current note while a couple of peasants wander past. Of course, the fact that the wall is covered with enormous stone figures all pointing at him doesn't help his cause. Surprisingly, not long after recording this, Patrick Warburton was swarmed by Disney lawyers, ordering him to sign over the rights to this "improvised song".
Almost happens in Treasure Planet when Jim and Ben are sneaking by the pirates to steal their dinghy. Surprisingly, no one wakes up.
Ben: SO WHAT'S THE PLAN?
In Gnomeo and Juliet, Benny's idea of a costume for an 'ultimate stealth' mission involves dressing as a daisy and strapping a spray can that rattles as he moves to his back.
Ironically, she earlier chided Gru for his habit of shouting "Freeze Ray!" before firing, which gave her enough warning to counter with a flamethrower. She then defied this trope by announcing her lipstick taserafter she fired it successfully.
In Margaret Weis & Tracy Hickman's The Death Gate Cycle, Hugh the Hand does this deliberately so that his assassination attempt fails. (It works anyway: taking advantage of the distraction, the person who hired him gets a Back Stab in on the mark, inflicting a serious but ultimately non-fatal wound.)
During a massive battle in The Wheel of Time series, Osan'gar/Aginor gets the idea to sneak up on Rand and Nynaeve and grab the power-amplifying Choedan Kal access keys away from them. Unfortunately, while Osan'gar can hold his own in a one-on-one fight, he is a Mad Scientist who has never been anywhere near a real battlefield. Predictability (and death by friendly fire) ensues.
...he began to skulk from tree to tree in what he imagined was a stealthy manner. It was toward the key that he skulked.
In The Silent Blade of the Drizzt novels the legendarily skilled assassin Entreri arranges an even duel between him and Drizzt in an attempt to finally see which one of them is a better fighter. After he loses he charges Drizzt from behind, shouting, and only survives because one of his allies protected him. Drizzt later concluded that he was trying to die.
A large number of characters in James Fenimore Cooper's novels announce their presence by stepping on dry twigs. Mark Twain roundly mocked this, and other features of Cooper's work, in his critical essay Fenimore Cooper's Literary Offences.
A variation appears in Dr. Jekyll and Mr. Holmes; when their investigation of Dr. Jekyll takes Holmes and Watson to an Edinburgh brothel to interview the madam, Dr. Watson — as a respectable gentleman — is a bit self-conscious and tries to approach the location in as stealthy and unnoticed a fashion as possible. However, his attempt at stealth is so laughably ostentatious that Holmes, amused, tells him he might as well just walk in there normally, since anyone who might recognize Watson would also have to explain his own presence at the brothel, and Holmes and Watson at least have a legitimate reason to be there.
In the Magic: The Gathering novel Ravnica, Agrus Kos tries to throw a spear into a half-demon's back while it is distracted. Unfortunately, he shouts as he throws it, causing the half-demon to turn around in time to block it.
Agrus Kos: Oops.
Bell Borca: Yeah, next time don't yell first.
Extremely played straight in The Amazing Maurice and His Educated Rodents. Wrong Genre Savvy Malicia lives her life trying to apply storybook logic to real life. So in one scene when she's trying to be stealthy, the book describes her thought process of how if you are going to be stealthy, you ought to make it very obvious how stealthy you're being so anyone who sees you knows you're being stealthy and shouldn't notice you. So she "sneaks" around in cartoonishly exaggerated and highly obvious fashion, completely oblivious to the bemused stares she's attracting.
Maurice and Keith just walked along behind her. No-one even looked at them.
Captain Carrot is doing the same thing at the start of Night Watch, though he doesn't mean to. Carrot is just so honest he can't help it, and to make matters worse, he's The Hero and therefore always the center of attention whether he wants to be or not.
Oh, he ducked and crept, and against all logic that made him more noticeable. He didn't understand the art of thinking himself invisible.
Another inversion: Crispin Horsefry in Making Money sneaks off to a meeting one night, and the Igor who welcomes him offers: "Allow me to take your highly notitheable black cloak, thur."
In the Warrior Cats series, there's a scene in Eclipse where RiverClan cats attempt to sneak through ThunderClan's territory. Unused to thick undergrowth, they make a lot of noise just walking through, and then they have a whispered argument about how noisy they're being.
Live Action TV
In the Doctor Who serial "Time and the Rani", a monster spends an episode and a half stalking the heroes, then finally gets the drop on them, pops up from behind a rock a foot away, and roars triumphantly for ten seconds.
The "silent countdown" mode for the Self-Destruct Mechanism in the various Star Trek series seems to apply here. While the application seems obvious enough (by having a self-destruct that won't alert the enemies as it counts down), this is ruined by the fact that it has a ship-wide alert declaring that it's been activated. Strangely, in at least one episode of Star Trek: Voyager, the silent countdown of the auto-destruct apparently worked perfectly, including no announcement over the ship's comm system to alert the bad guys—or the rest of the crew.
That being said, it's called a silent countdown, and not a silent self-destruction sequence.
From the obscure '90s Puppet sitcom Greg the Bunny, Tardy the Turtle was told to be quiet during a paintball game so he wouldn't give away their position. He affirms that he understands, then starts singing "I am singing the quiet song, the quiet song, the quiet song."
Subverted in Monty Python's Flying Circus in one sketch where a married couple is in bed and the wife is being courted by a succession of paramours who sneak into the bedroom (including a Mexican rhythm combo, who actually ask the husband where his wife is). Several times the husband wakes up, asking if his wife just heard something, and the wife assures him it was just the plumbing or a tree branch outside, excuses he always happily accepts. He eventually gets up to use the bathroom, somehow missing the roomful of people as he does so. (The "punchline", in typical Python fashion, is deliberately anticlimactic: in a cut to the bathroom, we see the husband is having an illicit tryst of his own, but is worried his wife is starting to suspect something.)
The MythBusters narrator invokes it when Jamie tries to move silently through an airduct using magnets. Magnets that were clanging with the air ducts:
Rob Lee (US Narrator): Here's some key phrases from the surreptitious entry heist manual: Be the breeze [clang]. As light as a feather [clang]. The foot fall of a kitten [clang].
Then Adam: "Why, Thor, the god of thunder, is trying to enter my building!"
Invoked by Adam in the Escape From Alcatraz myth:
Adam: (while pounding on something with a hammer) [bang bang bang] "Wait! Was that a guard?" [beat] "No?" [bang bang bang]
Another prison escape myth (Can salsa be used to erode through the bars) had Adam making a very noisy drill made from a vacuum he "stole."
In the safe cracking myth, it was mentioned that the safe is stated to take professional safe crackers five minutes to crack the safe. Of course, it is also shown that the professionals don't need to worry about stealth, so it is less "putting your ear to hear the tumblers move" (or even "pry off the lock and push the tumblers into place with wire", which, unlike the stethoscope method, actually worked) and more "smash it with sledge hammers."
One of the many reasons the Babylon 5 episode "Grey 17 Is Missing" is considered one of the worst episodes of the show is that the "ultimate predator" is about as subtle as a sledgehammer in a bell factory. At least part of it was the director's fault, as JMS had called for a Nothing Is Scarier approach where the monster was always in shadow, but the director chose to show the monster in too much light.
Pixelface: After Alexia destroys Clairparker's favourite shirt, Kiki loans Clairparker one of her outfits. After Claireparker wears it in her game, she discovers it very hard to hide from zombies when your outfit literally lights up and glows in the dark.
Let The Blood Run Free had Matron Dorothy Conniving-Bitch, who snuck around while saying "Sneak sneak sneak sneak sneak". Subverted only by virtue of it being the least OTT thing about the show.
In the Jim Henson television special The Tale Of The Bunny Picnic, the song "Bunny Stew" is sung by the farmer's dog as he is following Bean. Most of the lyrics are about how stealthy the dog is being, and despite him singing them rather loudly, Bean doesn't seem to notice him.
Buffy the Vampire Slayer. This causes problems when the Scooby Gang work with special forces soldier Riley Finn. Riley works for the Initiative, a Government Agency of Fiction that tracks down demons and vampires to capture them alive for experimentation, whereas Buffy and her friends act as The Bait to lure them into attacking so they can be killed. This means Riley has to tell off the Scoobies for munching chips and talking loudly while he's trying to sneak through a graveyard.
Toward the end of the Snow Goons arc, Calvin and Hobbes sneak out of bed and go downstairs, shushing each other to keep quiet, then once they're out in the open, Calvin starts laughing loudly and yelling for the Snow Goons to die, waking his parents.
Dungeons and Dragons: The Marshal base class from the Miniatures Handbook motivates others with his force of personality. Mechanically, this is done by auras which allow him to apply his Charisma modifier to various checks. You can choose an aura which adds to Dexterity based checks and skill checks, which means that you can make a party sneak better by telling them to be quiet. When combined with a Bard ACF that allows them to play a song granting bonuses to Move Silently, the results are hilarious.
Warhammer 40,000: The Imperial Infantryman's Uplifting Primer on how to take out an enemy scout: "Recite the Litany of Stealth to decrease your chances of being heard. However, if one looks in the back of the book, where the litanies, blessings, and prayers are, one will note the absence of a "Litany of Stealth". In other words, to kill an enemy scout without being heard, shut the frak up!
There is, however, the Prayer of Invisibility (which in a bit of Genre Savvy, is to be whispered), used when hiding in ambush.
Warhammer Fantasy gives us an Orc army that was briefly famous for their stealthy night raids until the boyz started bellowing the new battlecry "Youz can't see us!".
Meanwhile, back in the 40K verse, Ork camps can easily be snuck up on raving band of Chaos Marines, since seeing intruders makes all Orks "WAAGGH ATAK!" rather than "raise alarm." Gunfire doesn't attract much attention either, since random shots are the norm rather than the exception.
Ninja Burger gives players a bonus to attacks if they're willing to shout a sufficiently impressive Battle Cry during combat... the instruction manual notes that this is entirely antithetic to Ninjutsu, and even the game itself (where just being seen at all requires the player character to cut off a finger in dishonor), but it's what the Ninja do in movies, so that's what the game runs with.
Policemen and Pirates: "He thought he heard a noise...HA HA!"
And the lines quoted above are followed by the policemen accompanying them ("Tarantara, tarantara") without the pirates realizing the policemen are there. Definitely Oper(ett)a Logic there. And shortly after the end of the song, the Pirates move to hide, singing the line "Yes yes, the Major General comes". It's then repeated by the Policemen. Then it's repeated by the Major General himself, as he leaves his house.
Modern G&S adaptations like to ratchet up the absurdity even more:
In some productions for the chorus, they'll pull out hats with brightly glittering sequins and star a chorus line. There's a particularly good example here. The fun really starts around the two minute mark.
One Broadway production had the Pirate King "accidentally" struck a cymbal in the Orchestra pit with his sword, even before the song started.
In one version a pirate actually discusses the plot with a policeman during the song, without ever realizing that it was a policeman!
The King's Singers, an acapella group, once covered the Trope Namer on a G&S tribute album. They missed the point and sang very quietly. It was terribly disappointing.
The Aria most likely to be listed as the intended target of G&S's parodic attack is "╔coute, compagnon, Úcoute" from Carmen. A very loud song about how sneaky you have to be to smuggle cigarettes.
In Les MisÚrables, Jean Valjean sneaks out of the Bishop's house after stealing the silver.
Took the silver, took my FLLLIIIIIIIIIIIIIIIGGGGGGGGGGHHHHHHHHHHHHHHHT!
...and is immediately captured.
The Templar Stalkers in Assassin's Creed: Revelations come with a Scare Chord and yell "Die Assassin!" before they try to kill you. They're really easy to counter, and that usually involves jamming their own daggers into their own mouths.
Thugs and Harlequins in Brotherhood will run up to you, then start a short cut scene to announce their presence.
Los Illuminados in Resident Evil 4 would often laugh or say "I got you!" in Gratuitous Spanish when trying to sneak up behind you. Some of them actually shout "Behind you, you idiot!" in Spanish. Then again, maybe they were just too crazy to understand the benefits of a stealthy approach.
Somehow, The Legend of Zelda's Link can always stay unnoticed as long as he's out of sight no matter how loudly he grunts and screams.
Happens occasionally in online multiplayer games where the characters speak. Sneaking up on people in Gears of War gets hard when one of your teammates (here's looking at you Cole) suddenly yells "Oh YEAH baby!" A similar effect happened in Star Wars Battlefront 2, where Jedi/Sith characters would randomly say phrases, which, in Jedi to Jedi matches, could really screw up a surprise attack.
While in Splinter Cell multiplayer mode, enemies can hear your real-world teamspeak if you don't keep it down.
Performed masterfully in Metal Gear Solid, where four invisible mooks that are on the elevator with Snake, literally close enough to reach out and touch him from the moment he steps on, must sit and wait for our hero to riddle out what's going on in an absurd fashion over the radio despite the fact that all four of them have machine guns. Conforming to the mook code even further, one of the mooks announces their presence after the hero has already figured out what's going on with a hearty, "Too late, Snake. Now you die!" Of course no, no he doesn't. Even stranger in that they can't hear what he is saying over the radio, since codec communications directly stimulate the receivers they are tuned into. He's talking but they can't hear it.
Fallout 3 companions can complicate the stealth approach by hollering to the enemy, "Come on out and let's fight face to face!"
Let's not forget the Prototype Medic Armor. It's a lovely set of Powered Armor that protects you from radiation and gives you morphine when you need it... and if it notices an enemy anywhere in the vicinity, roars out, "TIME TO KICK SOME ASS!" at the top of its lungs.
Fallout: New Vegas continues this; whenever you crouch (start "sneaking"), your companions will say something to mark the occurrence. Depending on the companion and which of their lines happens to play, this can range from a whispered word of agreement, to a full sentence at normal volume, to shouting. None of it affects your stealthiness. The funny thing is that Lily, a Super Mutant who shouts out how she knows how to keep quiet is actually the stealthiest of the companions since she'll activate a Stealth Boy upon sneaking.
Also played straight in both games with certain melee weapons. In 3, all melee weapons are considered quiet, so nobody notices anything when you use a rotary saw to dismember a person right next to them. New Vegas is worse, as it adds actual chainsaws, punch-triggered shotguns, and glowing energy axes to what guards fail to notice.
In BioShock, it's not always easy to see splicers slinking around the darkened corridors. They make life considerably simpler by constantly mumbling gibberish to themselves. This includes spider splicers, whose stealth is supposed to be their strong point. This is, however, probably justified by them all being quite insane.
Which makes the Plastered Splicers (stronger Spider Splicers looking like statues) in Fort Frolic the possibly scariest enemies in the game. Not only can they disguise themselves as statues (or just spawn right behind you), they are the only enemies attacking in absolute silence.
In the first two Brothers in Arms games, when ordering the placement of your squads in an ambush, the player character would bellow loudly, even if the enemy was quite close and not alerted of your presence. The third game, Hell's Highway, averts this tendency by introducing a situational mechanic that makes the player character whisper to his squadmates if the enemy is unaware.
None shall see me, though my battlecry may give me away.
In Grand Theft Auto: San Andreas, Carl and Ryder are ready to break into a war veteran's house and steal as much as possible; Carl suggests sneaking in rather than taking the place by storm. Ryder agrees that it's a smart idea, but then follows this up by howling "COME OUT YOU OLD BASTARD!" at the house.
The Flying Machine in Warcraft III has a similar quote:
"They'll never hear me coming!" *aircraft engine splutters*
Don't forget the Pit Lord from the expansion pack:
"I think a certain... finesse is called for here. GRRRAAAAAGGGGHHH!!!!!" *sounds of violent killing and screaming*
Can happen via Gameplay and Story Segregation in Mass Effect 2, given the existence of a stealth mode and Commander Shepard's habit of loudly exclaiming whenever he/she finds some variety of weapon or loot. The volume of these exclamations seems to be unintentional, though, as they are considerably louder than most other examples of in-game dialogue.
In the final portion of King's Quest V: Absence Makes The Heart Go Yonder!'', you're sneaking through the evil wizard's castle and one of the things you can interact with is a gigantic pipe organ, which will of course end up alerting the wizard to your presence and get you force choked to death.
In the climax of Star Wars: The Force Unleashed, Emperor Palpatine is trying to tempt Starkiller to turn to the Dark Side when Rahm Kota breaks his bonds, screams "No!", steals Palpatine's lightsaber with the Force, and lunges at the Emperor. Palpatine looks up, momentary bewildered, before blasting Kota mid-lunge with Force Lightning, indicating that his attack could have worked if he hadn't yelled. On the plus side this does distractPalpatine long enough for Starkiller to break his bonds, so it wasn't completely pointless.
In League of Legends, Teemo has the ability to stealth when standing still. This is very helpful if the enemy doesn't see you turn invisible in a blatantly obvious manner. In which case he will stand right next to you, call in his team and you will be subjected to a large number of area effect spells and die.
There's also a video of a Teemo who stealthed in a bush, waiting to ambush an enemy at the start of the game, and made the mistake of using his taunt emote as the enemy walked by. While this didn't break stealth, the enemy did hear it, letting him know Teemo was in the area and allowing him to guess exactly where he was.
In Team Fortress 2, inexperienced spies frequently end up dying because they use mic chat while disguised, putting a speech balloon above their character that's their real team's color and ruining the disguise. The decloaking noise for the default Invis Watch is also pretty loud, and a replacement "Pocket Watch" which allows you to fake your death is even louder. In a subversion, when disguised any keyboard voice command will be in the correct voice for that disguise. This includes announcing that you've found a spy. Fun thing to watch as long as there's no pyro's nearby.
This can also happen to an extent with other classes if a player micspams or over uses keyboard commands while trying to sneak up on other players. More than one Scout has met their end because their player couldn't resists spamming the "Medic!" button and tipped off a nearby enemy to their presence.
This only matters in Alltalk servers (all players can hear each other's mics, regardless of whose team they are on), which nobody would take seriously enough to matter anyway.
The Elder Scrolls III: Morrowind's Tribunal expansion kicks off with the player character being attacked by an assassin while sleeping. Evidently he isn't a very good assassin — he starts yelling abuse at you as soon as he attacks, and the game displays the message "You are awakened by a loud noise."
In Street Fighter X Tekken, Raven is halfway through outlining his plan to distract and sneak up on Vega and Balrog when his partner Yoshimitsu leaps at them yelling at the top of his voice. It's honourable, apparently.
Final Fantasy VII can allow the player to pull this. When outside the Shinra building, Tifa and Barret suggest different plans for how to get to the upper floors to save Aerith. Tifa wants to sneak in the back and take the stairs, avoiding fights with Shinra soldiers, while Barret just wants to burst in the front door, guns blazing. The player can then make Cloud agree with Tifa in the Dialogue Tree, only to instead follow Barret's plan.
In the original Doom game, you can sneak around while carrying a running chainsaw. Just don't punch the air with your bare fist, that makes enough noise to alert monsters.
When Elan makes a low roll on his Move Silently check, he decides to let the rest of the party know by shouting "I GOT A 4!". He does it again in #766, except this time he GOT A NINE! (he's wearing magic boots that give him a +5 bonus to Move Silently checks).
Lampshaded in Demyx Time, with Demyx proposing that the entire Organization sneaks up on Sora and ambushes him, screaming "ATTACK!". He's laughed at, until Marluxia proposes that they all take it in turns to monologue in front of him before attacking. Xemnas commends this approach. Demyx tries to get some credibility back by suggesting that they all sidle up, before suddenly screaming "We are NOT going to attack you!" Needless to say, not a lot of progress is made.
When Caboose from Red vs. Blue goes to sneak by the Red Base, he makes a fairly good job of it except for the fact that he loudly whispers 'I am sneaking, I am sneaking...' as he moves a matter of metres away from the Red team-members. And then he moves his piece of cover with him, right along Grif's line of sight. Amazingly, Grif is the only one who seems to notice anything.
Also happens when Tex, Tucker, and Church are assaulting a compound. Tex rather unstealthily dispatches several guards who continuously scream and fire their weapons, and none of the other guards seem to notice. Until Tucker talks.
Variation: In The Simpsons, the Kwik-E-Mart's silent alarm says "SILENT ALARM ACTIVATED!!" when put into use.
The Venture Bros. episode where one of The Monarch's mooks attacks the new guy taking over, and yells "Semper Fidelis Tyrannosaurus"note "Ever Faithful Tyrant Lizard" for those who don't know Latin, he was going for the aforementioned "sic semper tyranis", and came up with the closest Latin words he could remember, "semper fidelis" (the US Marines motto) and a dinosaur.
Avatar: The Last Airbender had Hahn's attempt to attack Zhao. He was disguised as a soldier and could has easily snuck up and attacked him, but instead opted to take off the helmet and declare his intentions to "Admiral Chow" before charging and was immediately thrown off the ship to his death.
"Sokka, sneak attacks don't work if you yell it out loud."
Sokka has a problem with this. In the second episode, he charges dramatically at Zuko, club raised and screaming at the top of his lungs... and gets kicked into a pile of snow. He keeps trying, though, but the results are the same every time. Points for tenacity, we guess.
Futurama had Bender shout, "prepare for a surprise attack!"
At least once in Family Guy, Peter sings a typical movie sneaking song as he sneaks into an office. There's no one around to hear, but still.
When Carter loses his fortune in "Peterotica", he and Peter try to figure out how to make money. Peter suggests he steals cash from Lois' purse while he distracts her on a unicycle. As Carter reaches for it, he tells Peter "Ca-Caw. I've got her wallet. Ca-caw". When Lois turns around, he tells her to look at the unicycle.
In the earliest Elmer Fudd cartoon, though, he is actually making an effort to speak quietly.
An episode of Batman: The Animated Series had him teaming up with Harley Quinn against the Joker. As they were sneaking into his hideout, Harley is behind Batman saying "Sneak - Sneak - Sneak". She stops when Batman turns around and glares at her.
Similar to the The Pirates of Penzance example above, one episode of Donkey Kong Country features Bluster Kong singing about how's going to steal the Crystal Coconut and use it to win Candy Kong's heart...while actually sneaking into Cranky's Cabin, where it's kept. He even shushes Cranky for making a noise while the old ape's dozing!
"Here I go creeping/Shh, don't make a sound"
Chowder: "Mung will never hear us sneaking about over the noise of all these smashing plates!"
In the My Little Pony: Friendship Is Magic episode "Over a Barrel", Pinkie Pie utterly ruins Rainbow Dash's attempt at stealth by getting her so irritated that she yells at Pinkie to stay quiet. This, of course, gets them found out.
Jack Spicer: When hunting the elusive Wu, you have to be as quiet as a cat. (trips over a potted plant)OW! OW! OW! OOH THAT HURT!
"O-U (The Hound Song)" from The Electric Company was an animated segment where a hound (voiced by Tom Lehrer) sung loudly about how he dare not make a sound.
The Big Knights: The Big Knights are not exactly stealthy. This is especially apparent when they don the hats of invisibility.
Invader Zim gives us the Megadoomer, a giant, heavily-armed assault vehicle equipped with its own cloaking device. Unfortunately, the stealth mode is offset by three factors; 1) It doesn't have a battery, so you need to plug it into something using a highly visible cord. 2) Each step it takes causes the Earth to shake. 3) the designers were obviously fans of Wonder Woman...
Zim: Now, fight an enemy you cannot see!
Dib: You're right there.
Dib: There! Your mighty Irken cloaking device cloaks the robot, but not you.
Dr. Mindbender ask some new recruits how they would assassinate a Joe in the field. After some practical plans, the last recruit says that he would use a cobra to kill the Joe and loudly scream COBRA!. Mindbender agrees with this plan.
In ''Hogan'sHeroes", Hogan tells Roddy Piper he needs his stealth to take the guard out quietly. Roddy starts by adressing the officer, "Hey hey hey, you fucking Nazi." He is anything but quiet as Hogan Face Palms.
Two of the Mandarin's mooks are on guard duty. They comment how easy it is to detect Iron Man trying to infiltrate the base now that they removed all the carpets. They start hearing loud clanging foot falls. One asks the other if they should sound the alarm, he replies that he still sounds quite far off so there's no rush.
In The Super Mario Bros. Super Show episode 'The Great Gold Coin Rush', Mario leads the group into a town currently under King Koopa's control. As he's saying how they don't want to make any noise, he trips over a bucket with a loud crash. It turns out that the town is empty, as Koopa is forcing everybody to work in his mines.
In the Adventure Time episode "The Lich", Finn and Jake try to sneak up on Princess Bubblegum so they can take the gem from her crown. They end up crashing through the roof of her bedroom.
In Aaahh!!! Real Monsters a burglar was robbing a mall and breaks several glass windows which make loud noises, and the mall cop in the mall didn't hear any of it and was sleeping on the job.
The Silk Road, an anonymous drug dealing ring, was undone by a string of laughable slip-ups that defeated the whole purpose of using Tor for the server. Highlights include the head honcho using the same screen name on a web about shrooms and on a job offers website, asking at Stack Overflow for details on how to connect to Tor, and registering for all of the above with an email made of his full name and linked to his college profile. Also discussing his illegal drug-selling website on his Linkedin page which also was created using his real personal information.