Sometimes people are so tense it doesn't take much to scare them. Cue either a smarty alec team-mate or a foe with the taste for irony simply stating "Boo". This results in the jittery character either freaking out or begin running in a panic while screaming. Usually a Comedy Trope but appears in genuinely scary works to show how threatening the monster/villain's presence is. Compare Cherry Tapping which is a minor attack downing someone rather than a minor spook and The Last Straw.
Examples:Anime and Manga
- In Episode 2 of the Little Lulu anime, Lulu says "Boo" to Tubby in a deadpan tone while pretending to be a monster, which sends Tubby running off screaming in terror.
- Shan-Yu greets the Emperor this way in Mulan. Played for scares.
- Space Jam, after the Nerdlucks transform into the Monstars.
Blanko: Hey, little pig... boo.
- In Madagascar, after Alex fights off the fossa, he scares off the few that remain standing with a simple "boo".
- Used by the Lunar Ghost in the first Scooby-Doo live action movie. Naturally, Scooby screams.
- The Joker Pulls this on Vicki Vale in Batman. Understandably, Vicki screams.
- Undercover Brother. When Lance gets into the limousine next to James Brown he's clearly nervous. James Brown says "Boo" to him and he almost jumps out of his skin.
- Played with in Ghost, where the title character freaks someone out by writing "BOO" on his mirror. Considering that Sam is, well, a ghost, and the person he's freaking out is watching the word trace itself into a fogged mirror, it's not really a "minor" scare at all.
- In The Ninth Gate, Boris Balkan does this after killing Liana in front of her coven, making them all jump.
- In Pete's Dragon, Elliot does this to Hoagy the second time they meet, when Hoagy comes to deliver the message that Pete's been captured.
- The Scarecrow pulls this on Judge Death in "Judgement on Gotham", a Batman /Judge Dredd crossover comics. Death was not amused...
- Christopher Champion (Tempest) pulls this on a guard at a museum where the Scanner One spaceship was stored in the Atari Force series.
- In Bloom County, wheelchair-bound Vietnam vet Cutter John is having tea with his girlfriend's mother. He asks if she's nervous, since some people are nervous around the handicapped. She, smiling, says no. Last panel is him saying "Boo." and her tossing her tea and shielding herself.
- In one Halloween comic strip of FoxTrot, Jason dresses up as a ghost and practices booing. The problem is that he's booing not like a ghost, but like a dissatisfied spectator.
- When Mike and the 'Bots had The Screaming Skull inflicted upon them, Crow decided to pull a prank on Mike — dressing up as a skull and giving a feeble "raaar." The resultant meltdown by Mike has to be seen to be believed.
- In Spyro 2 Ripto does this to Moneybags right after Moneybags said he'd give Ripto a piece of his mind if he was there.
- In Halo 2, the Master Chief does this after the Gravemind teleports him into High Charity and he finds himself standing right next to a very startled Grunt. The Grunt reacts by screaming in terror, throwing his gun, and running away. The MC then calmly grabs the gun and begins fighting his way through the Covenant capitol.
- Variation in Brawl in the Family. Dedede and Meta Knight are stuck together by a Gooey Bomb and as Dedede is sweating Meta Knight flatly says "Boom" to get a rise out of Dedede.
- Gunnerkrigg Court on page 153, when Mort tries to sneaks up on Kat and Annie sneaks up on him.
- In Punch an' Pie, Angela comes home to this when she meets Erik for the first time.
- In the Tex Avery cartoon Slap-Happy Lion, a mouse scares a lion with a flat boo. Doing it repeatedly drives the lion mad.
- Droopy, given his nack for Offscreen Teleportation has done this a few times.
- Variant in Two Stupid Dogs. The big dog will scare cats by going to up to them and giving a deadpan "Woof." The cat will then comically seize up in fear.
- In the U.S. Acres episode "I Like Having You Around", Wade tries to convince a bug that he's not afraid of him. However, the bug just says "Boo" to him in this manner, causing Wade to freak out and run in a panic.
- On the subject of U.S. Acres, the original strip had an example of Roy trying this on Wade after tying his beak up.
- Raven does this to Beast Boy in an episode of Teen Titans.
- This was also exhibited in the first act of the Mr. Bogus episode "Bookstore Bogus" with a pair of ferocious worms that Bogus encounters in a book about bugs. When Bogus claims that he's not afraid of them, the worms look at each other for a few seconds before saying "boo" to Bogus in this manner, causing him to run in a panic with the worms hot on his tail.
- In a first season episode of The Venture Bros. 24 threatens Brock Samson with a lightsaber. After finding out the beam isn't solid, Brock leans in close and says "boo" making 24 run away. 3 seasons later after 24 Took a Level in Badass, Brock tries to do the same thing, and ends up getting round house kicked in the face.
- Chow does this to Tohru in Jackie Chan Adventures when he gets the first Oni Mask. Tohru, who has an immense fear of the Oni, freezes in terror before Jade tells him to snap out of it. Tohru later returns the favor when the mask is removed, and Chow flees with his tail between his legs.
- On one SpongeBob SquarePants, SpongeBob and Patrick claim that they weren't frightened by a scary movie. A flat boo from Squidward proves otherwise.
- An episode of the Beetlejuice cartoon has Lydia's friends look into the hollow of a tree they believe to be haunted. Beetlejuice calmly says, "Hey, how ya doin?" Lydia's friends flee in terror.