A character wields something in a threatening manner, the music builds, and then... the character does something utterly benign with that thing. It is often Played for Laughs.
It can overlap with Mistaken for Murderer. While that trope is an entire plot leading up to the reveal, this trope does it in less than one scene. The overlap is that such a plot can have several moments like this.
Compare Stab the Scorpion.
In Mahoujin Guru Guru, the heroes walk into the old witch's house to find her in the dark, cackling madly over a steaming cauldron of god-knows-what... it turns out she was just boiling potatoes.
Nike: Can't you do it normally?!
Once you've seen a certain arc of Higurashi No Naku Koro Ni, you begin to realize that Rena's walking down the road with that billhook of hers back in the beginning wasn't out of any murderous intent, but because she had used it to hack things out of her way and pry out a statue from the garbage dump.
In an Alternate Universe detective episode of Sayonara, Zetsubou-Sensei, while investigating a multiple homocide, Nozomu witnesses the girls run out of kitchen with knives and repeatedly stab something lying on the yard. Then they tell him that they were going to butcher a chicken for dinner, but it almost got away.
It might be a bit of stretch but the famous "Osaka With a Knife" scene in Azumanga Daioh seems to partake of this trope. As Osaka walks toward Yukari, Yukari's eye widens in terror. The next shot is of ketchup being squirted on an egg so for a split second, it looks like Osaka stabbed Yukari in the eye.
Yukari then looks like she's going to soil herself when Osaka mutters "Aw man, I messed it up..." She was trying to wake up Yukari by banging pans together but grabbed...a knife instead (Which isn't the source of the mess-up. As far as Osaka was concerned, she messed up because Yukari had already woken up before she could start).
In one of the Ranma ˝ OVAs, Kasumi has been possessed by a demon, at one point she raises a knife while laughing maniacally while the others cower in fear, then she uses it to chop some vegetables.
An early episode of The Wallflower shows the guys being terrified of Sunako's creepy demeanor and maniacal laughter, with camera angles focusing on closeups of the knife and her face as it gets splashed with blood... while she's cooking them an excellent dinner. The blood? That came from a fish she chopped up.
Hell; Toht's own allies literally let out a relieved sigh at that part.
This was actually based on a gag from a deleted scene of Spielberg's previous film 1941note which means Christopher Lee first got to do it!. He swore he'd try to put it in every later movie he made until it stuck and luckily got his wish right away.
Parodied in Family Guy by the Russian prime minister who uses a crossbow bolt to hang his tie and lights a cigarette with a lighter that looks like an assault rifle aside from doing the above gag.
The movie version of Harry Potter and The Prisoner of Azkaban has this. The executioner raises up his axe, the music plays and crows fly off... Later it's revealed that he only chopped a pumpkin in half out of frustration because Harry and Hermione went back in time and freed Buckbeak.
The same trick is used in the book. Although this time the axe is swung into a fence.
Used in Disturbia where the suspected killer sneaks up on the woman with a knife and cuts off the tag on her dress.
In Mars Attacks!, the aliens toss an ominously glowing sphere into the White House's War Room. They shake the object, revealing it to be a snowglobe, point, laugh, then shoot everyone anyway.
The Monster Squad pulls this off on the audience: After the kids are confronted by the Scary German Guy, the next scene shows him wielding a large butcher knife and threatening that their time is almost up...because it's their last chance for more pie. Scary German Guy is bitchin', indeed.
M might be the Trope Maker: near the end, a beggar witness points out Hans Beckert (Peter Lorre) as being the child murderer; unfortunately, Beckert has already ensnared his next victim and is taking her to a candy shop. A criminal follows them, hoping to corner Beckert and save the child, and starts forward in horror as Beckert pulls out a knife... only to use it to cut the peel off an orange. Audiences at the time, familiar with the all-too-fresh string of murders which inspired the film, were notamused.
A particularly dark form of this shows up in Trick 'r Treat, in which the "innocent" explanation is almost as bad as what the audience had first assumed. It really looks like Serial Killer Steven Wilkins just knifed his own son, Billy. But no, he was just helping Billy carve a jack o' lantern out of a human head.
In their final fight in Rush Hour 2, Dragon Lady Hu Li grabs a pair of chopsticks and then uses them to tie her hair back before she takes on Carter.
Diamonds Are Forever. While pretending to be a waiter, Mr. Wint raises a icepick-like device high in the air next to James Bond. He then strikes down but not to stab Bond: he drives it into the cork of a wine bottle, then uses it to extract the cork.
And still something similar happens in Hot Shots: Part Deux as Topper Harley and Michelle Huddleston "reenact" a scene in Basic Instinct. After tying Topper to the bed, Michelle slowly grabs a screwdriver under the mattress. She raises it over Topper's head and stabs...a loose screw on the bed's frame which was squeaking loudly. Michelle tightens the screw and oils it even. She then tests the bed and once assured the squeaking had stopped, Michelle proceeds to romance Topper.
In The Curse of the Were-Rabbit, when Lady Tottington asks what Wallace and Gromit are going to do with the bunnies they have caught, the next shot has Gromit holding something on a cutting board and raising a big knife...and then he starts cutting up carrots for the bunnies.
In Harold & Kumar Escape from Guantanamo Bay, the duo end up in a black neighborhood and crash their car into a fire hydrant, spraying water everywhere and causing general havoc. The residents silently and purposefully collect tire irons and similar implements and march towards the accident scene. H&K flee in panic. Turns out the residents were planning to help fix the car.
Played with in The Professional. Jean Reno is teaching a young Natalie Portman how to be an assassin. They set up a sniper rifle on the roof and shoot a politician jogging in the park, only for us to realize that it was a paintball gun.
In The Hand That Rocks The Cradle, evil nanny Peyton sneaks into baby Joey's room late at night. She menacingly approaches his crib - pillow in hand - as the music builds. She ends up just placing the pillow under the baby's head.
Whacko, a Psycho parody, opens with one of these, done by an actual serial killer who uses a halloween pumpkin motif.
In Crash Peter, who is hitchhiking, is picked up by officer Hanson. They awkwardly try to bridge the gap between their cultures but Hanson, at one point thinking that Peter is drawing a gun on him, shoots and kills Peter. It turns out Peter was actually going to show him the St. Christopher figurine he always carries with him.
Slight variation in Romancing the Stone, since no prop is involved. After bring the villain the map he wanted in exchange for her kidnapped sister, Joan Wilder has nothing of value left to keep said villain from eliminating her. With the music playing menacingly, the villain growls "Joan Wilder ... you and your sister........are free to go!"
Men In Black. While facing the Mexican immigrant, K pulls out a knife in a threatening way. He swings it forward toward the immigrant - and slices open the immigrant's clothing, revealing an alien hiding inside the clothing and holding up the immigrant's "head".
The Wrong Box begins with the establishment of a tontine - a contract where a sum of money gets inherited by the last surviving member - at a boys' school. A series of quick vignettes shows the members dying off over the decades until it settles on a bedridden, elderly man, one of the last two survivors. His grandson picks up a knife, walks up to him - and hands it to him to open a letter.
Older Than Print: In Romance of the Three Kingdoms, Magnificent Bastard Cao Cao, on the run from the law (long story), takes refuge with a friend of his father's. Said friend runs off for a while, leaving Cao Cao to wait. Cao Cao overhears the sound of a knife being sharpened and a whispered: "hurry up and make the kill!" Cao Cao charged into the kitchen, murdering everyone in sight... before discovering that the intended victim was a pig.
In The Year of the Boar and Jackie Robinson, when Shirley has just started school in America, she notices a huge stick by the window and thinks it's for beating disobedient children, like how her teachers in China used a bamboo cane. That same day, she agrees to sneak off of the school grounds with some other students, so they can buy lunch elsewhere. When she returns to class, she sees the teacher getting the stick and thinks that her escapade was discovered and she was going to get beaten for it... only for the teacher to use the stick to open the window.
In the Angel episode "Bachelor Party", when Angel is spying on Doyle's ex-wife's fiance, he sees him taking on a demon aspect and drawing out a knife. One Super Window Jump later, it's revealed that she knew about him being a demon, and that the knife was to cut the strings on a parcel.
In what may be a subversion Holtz draws a knife out of his sleeve when one of his followers questions his orders; when she ends up agreeing with him he uses it to peel an apple.
Arguably, this trope is the whole point of the Dexter title sequence, the difference in that everything he does is in plain view, while still keeping the menace.
The season two opener repeats the season one opener, ending with the words "This is the only way I know how to survive. I'm coiled and ready to strike..." - zoom out to show Dexter bowling and missing a pin - "Although a Spare will do."
At the beginning of an episode in season four, we see Dexter wielding a large knife and making threats about how his target's days are numbered. Pan back the camera to show Dexter addressing a thanksgiving turkey.
On a Halloween-themed episode of That '70s Show, Fez is spying on Bob from Eric's bedroom while in a wheelchair. He starts to think, based on a garbage bag, an dirtied apron and a butcher knife, that Bob killed Midge. However, it turns out that Midge is out of town and Bob is just carving pumpkins and taking out the trash.
In ALF, Alf spies Mr. Ochmonek burying what turned out to be a side of beef in his back yard, while Mrs. Ochmonek was out of town. The beef also accounted for the bloodiness of his bathtub.
In Reaper Nina, who was previously trying to kill Sam, lunges across the table towards him. It turns out she's going for a steak, and just has (literally) demonic table manners.
The Buffy episode "All the Way" features a creepy-looking man wielding a knife and talking about how he's going to give Dawn and her friends "something special" for Halloween. Turns out it's a baked dish.
Another episode in Season 2 does this. The group is together in the library preparing and sharpening weapons. Buffy pulls out a knife... and the camera zooms out while she chops vegetables.
Subverted in El Chapulín Colorado. We see a woman with a knife as the music becomes intense, just to cut some cake, then she proceed to hide a gun in it.
A Dilbert comic (which later gave its name to one of the collections), "Bring me the Head of Willy the Mailboy" involves Dilbert being asked to complete this request. Dogbert freaks out when Dilbert shows him a bag obviously containing a head-sized, roughly spherical object, but it is then revealed to be a bowling ball.
One FoxTrot Sunday strip set things up like a scene from a horror movie, making it look like someone was being stabbed to death. It turned out to be Roger doing a poor job of slicing up a turkey.
The opening for Disgaea 4 shows the vampire tyrant Valvatorez stalking and murdering his latest victim: sardines. Fenrich is not amused by these shenanigans.
In Tekken 3, Kuma/Panda's ending has Kuma waiting behind a wall, only showing a sinister-looking shadow, looking like he's getting ready to attack Panda. But as she and Xiaoyu walk by, Kuma lunges forward with a bouquet of bamboo leaves, attempting to court Panda. Not noticing him, Panda and Xiaoyu just keep on walking.
In a possible allusion to the Romance of the Three Kingdoms example (see Literature), at one point in Dragon Quest V you can choose to stay at an obviously sinister-looking inn in a cave with a creepy old lady while travelling with your new bride. She hears something in the night and asks you to investigate but you've become paralyzed and from upstairs you hear the sound of a knife grinding...In the morning, it turns out that the old witch was just making sure you slept soundly while she sharpened your sword which gains a permanent attack bonus.
In the first The Simpsons "Treehouse of Horror" episode, the Simpsons have just bought and moved into a haunted house and get turned against each other by the house so each and every one of them (including Maggie) get a sharp implement of some sort and they go stalking after each other...except for Marge who's just using the big-ass serrated knife she picked up to spread mayo on a sandwich.
Another Simpsons reference sees Flanders chase Lisa up to the attic with an axe, muttering "time to put you away for good"... only for it to turn out that he was actually talking to the axe itself. In fact, that entire episode was a parody of Rear Window based on this trope, as Bart witnesses Ned Flanders' killing of Maude's favourite tree. It even has Lisa discovering a Schuman's farms head of lettuce and Jimmy Stewart watching Bart try to stop Flanders and concluding that "that sinister looking kid's coming to kill me!"
Another episode, "Cape Feare", had Bart becoming paranoid after receiving several death threat letters in a row from Sideshow Bob, and seeing Ned Flanders waving a Freddy Kreuger-esque glove with the words, "Say your prayers, Simpson...Because the schools can't force you like they should!" He then goes back to using his glove to trim the hedges.
Later on Marge is walking towards Bart with a big-ass pair of scissors saying, "I'm going to get you...some ice cream at the store because we're saving our money on Diet Cola!"
When he's in class Miss Krabappel says he'll be her murder victim...in the school play on Lizzie Borden.
Then Homer later arrives with a butcher knife and blurts "BARTYOUWANTSOMEBROWNIESBEFOREYOUGOTOBED??" Finally revealing the case of brownies Marge had apparently cooked in between scenes.
Then Homer goes Motor Mouth showing off his new stuff, shouting HEYBARTLOOKATMYNEWCHAINSAWANDHOCKEYMASK.
On a completely different episode, Bart and Lisa think Sideshow Bob has kidnapped their dad. They see him through a window stabbing what looks like a human head and burst in to find that Bob was actually stabbing a clay bust of Krusty to aerate it (although he seems to enjoy it an awful lot).
Another episode ended with Moe holding up a knife at Neil Gaiman and saying he was going to do something he wanted to do for a long time. He then slices a pineapple and congratulates him.
Futurama: When preparing a cake for Nibbler's birthday, a jealous Bender remarks that it will be a cake "They'll never forget", grabs a box of rat poison and...pours it next to a rat hole by the floor. Then puts the box away and starts making the cake.
And in "Nightmare on Wilson Way", we see Bloo tying Mac to a bed and then raising an executioner's axe...before bringing it down to cut a sandwich in half.
In one episode of Spongebob Squarepants, Spongebob finds Mr. Krabs abusing captive jellyfish for their jelly. Spongebob grabs a wrench, and Mr. Krabs asks what he's going to do with it. Spongebob angrily says "Something that should have been done a long time ago!" before tightening a bolt and saying "This squeaky bolt has been driving me crazy."
In one episode of Jackie Chan Adventures, Jade (outside her body) sees a demon (who had possessed her body) going somewhere with a knife. She panics, music builds, she unsuccessfully tries to warn Jackie, cut to Possessed!Jade holding up the knife and...cutting an orange with it.
In Rocko's Modern Life we see Rocko saying he had enough of Heffer and then brings out a hammer and lunges to beat him...then it turns out he was talking about his busted vacuum cleaner.
And of course the episode where Rocko sees Bev Bighead stab her husband Ed to death. Turns out it was just a bust made of hamburger meat.
In The Grim Adventures Of Billy And Mandy, a mace-wielding man known as "Lord Pain" comes to visit. There is a scene where Grim sees his silhouette performing a seemingly gory beating, and delightfully comments on how he is "mashing the kids like potatoes". Cut to inside, and it turns out he is mashing up actual potatoes for Mandy.
Another episode features Billy watching what appears to be a horror film, he cowers in fear as a killer is apparently carving up a victim with a chainsaw while laughing manically, it turns out to be a commercial advertising chainsaws and the man was using it to saw a log.
In part 2 of the pilot for My Little Pony: Friendship Is Magic, when the group comes upon a sea serpent distraught because of his mustache getting ruined, Rarity declares that she can't let "a crime against fabulosity" go unresolved, grabs one of the sea serpent's razor-sharp scales in her teeth and brandishes it menacingly upon which we hear a "thwack" and the sea serpent faints...turns out she was just cutting off a chunk of her own tail (though not nearly enough to reach her physical tail) to use as a hair transplant.
In The Road to El Dorado at one point during the song "It's Tough To Be A God", Miguel and Tulio have their suspicions that the villagers may realize that they aren't actually gods, and we see the villagers raise their swords to them and bring them down while they scream and we see what appears to be blood spray, it turns out they cut open some watermelons.
In a live-action episode of Aqua Teen Hunger Force where it's shown the cartoon is a story written by H. Jon Benjamin based loosely on people he knows. Toward the end of the episode, he goes into Frylock's/T-Pain's room with a sword, panicking his roommate as he raises the sword and... presents it to him saying he was just bringing his sword back.
Benjamin as Coach Mc Guirk in Home Movies buys a pricey sword collection he sees on tv and can't return them - he tries to use them as currency to buy groceries but comes off like a threatening sword-wielding lunatic.
Done in an early episode of Family Guy where Lois decides to run for school board president. However, Peter is devastated when he discovers that Lois agrees with the firing of his favorite former teacher:
Peter: I'm going to stop you the only way I can... (raising ax as if intending to strike) by killing you! - in the race for school board president (using ax to nail down sign advocating his election as school board president).