Damon: [in relief] Oh, child. You always knock me for a loop. You know what? [...] I'm gonna get you two.
Damon: One balisong. Two balisong. That's what you get.
The butterfly knife, also known as a balisong, is a traditional Filipino knife. Its design, with two rotating handles, allow it to be flipped open and closed. It will usually appear in the hands of a Knife Nut, who will perform a complex, flashy and noisy flip. Anything beyond a simple and quick opening is Awesome, but Impractical as the hand is vulnerable to a strike disarm throughout the manipulation. Less frequently, a character will flip one open without fanfare and use it to cut something.
The most common and recognizable design is skeletonized: holes in a line along each handle. The holes reduce mass, control balance, and add grip. Traditional balisongs incorporate wood into their handles with brass accents.
Note that butterfly knives are illegal in many jurisdictions, although "practice" balisongs (i.e. with a blank piece of unsharpened metal instead of a blade) usually aren't. In some jurisdictions, such as Finland, they are considered as just ordinary knives. Finnish cutlery company Hackman even produces a foldable puukko just as a balisong. (It is essentially a tool, not a weapon, though.)
The first butterfly knives have been manufactured in Spain in 1550. The oldest surviving dates to France 1710. The traditional balisong is said to be called the veinte y nueve because they are 29 centimeters long when opened, while another story goes that it is named after a lone Batangueño who fought off 29 assailants using one.
- In a commercial for San Miguel beer, Stephen Chow performs a manipulation with a butterfly bottle opener that impresses and attracts all the women in the bar. The bartender assists by sliding the bottle over in a bucket of ice. Butterfly bottle openers do exist, but the design used in the commercial (flat, large rectangular hole) must be wider than bottle caps. This extra width over knife blades adds weight, affects balance, and throws off flipping. Due to this inherent flaw, nearly all are cheap novelties.
- One of the street thugs in Samurai Champloo has a butterfly knife styled to resemble a Japanese blade, one of the many historical anachronisms in the show.
- Taken Up to Eleven in Battle Angel Alita. After losing her motorball racer body, Alita has its Blade Below the Shoulder converted into a Butterfly Polearm.
- Mai Thi Hoang, a.k.a. Eternal Feather from Soul Eater Not! is a Vietnamese Demon Butterfly Knife. She can transform her arms into butterfly knife blades, and it is even hinted that she might be an Autonomous Weapon.
- Rui Habashira from Eyeshield 21 uses a butterfly knife, since the hat of the Zokugaku Chameleons is playing up stereotypes of Japanese delinquents.
- Battle Royale: At the beginning of the movie, Nobu stabs Kitano with a butterfly knife. The attack triggers Kitano's resignation and later selection as the class's Program Director. When Nobu drops the bloody knife while fleeing, Noriko grabs and hides it. At the end of the movie, Noriko retrieves the knife from her desk before going on the run with Shuya.
- In Casino Royale (2006), Le Chiffre's bald mook uses a spearpoint butterfly knife to cut out Bond's tracker and to remove the chair's seat in preparation for the rope torture. It resembles a paratrooper knife in the first scene, but he flips it before and after the chair.
- Joey Pants' character pulls one on The Goonies when confronting them at the waterfall. He doesn't even bother with any fancy opening tricks and simply unfolds it because, hey, pulling a knife on a bunch of kids is probably going to scare them anyway.
- Face/Off: One of the most memorable appearances of the balisong in a movie is when Castor Troy-as-Sean Archer gives Archer's daughter Jamie a kris-bladed knife for protection after he rescues her from an attempted rape. It's ultimately used on him when he takes her as a human shield as Archer-as-Castor trains a pistol on him.
- Frank gets a minor awesome moment in The Punisher (2004) when an abusive boyfriend of Joanie's pulls one on him while drunkenly mumbling threats. Frank immediately punches the dude's nose in and takes the knife, expertly closing it and admonishing the guy not to play with knives before smacking him hard on his already broken nose with the hilt.
- In Falling Down, the main character upgrades his baseball bat in his first encounter with the gang members. The gang member flips it open in a threatening display, but can't complete the simple opening smoothly.
- Hit-Girl got two for her birthday. And then got quizzed on the correct name for it used in the Philippines.
- Later, a Mook tries to intimidate her with a fancy flip routine. She is less than impressed, pulling out one of the abovementioned gifts and doing a better one.
- The Mummy (1999) has Rick use one most prominently to pry a giant scarab beetle from under Jonathan's skin. In quieter scenes, he uses it to cut things.
- Two-Bit in The Outsiders carries a butterfly knife. In an early confrontation, he smashes a bottle on a fence, passes it to Ponyboy, and flips his knife open.
- One of the gang members in the diner scene in Streets of Fire whips one of these out. The hero smacks it out of his hand, then hands it back to the gang member with the challenge, "Try that again." The gang member does, with the same result. The hero keeps it and uses it a few times, flourishing it whenever he pulls it out.
- Buckingham is playing with one when he is talking to captured D'Artagnan in The Three Musketeers (2011).
- Chow Yun-fat's Gou Fei uses one during the first major fight of Full Contact.
- One of the Lords of Death brings one out in Big Trouble in Little China, along with a telescopic baton. He doesn't actually use them though, just waves them at Jack until another guy trips Jack up from behind.
- Hannibal Chau brandishes a gold-plated one during a few scenes in Pacific Rim. He later uses it to cut out of a Kaiju's stomach.
- At the start of Transporter 2, a carjacker pulls one on Frank with accompanying flashy opening. Frank kicks it out of his hand, catches the knife by the handle, does his own flashy moves up against the carjacker's throat, pauses to enjoy the Oh, Crap! look on his face, then knocks him out with a punch.
- In Battle Creek Brawl, Jerry's second-to-last fight is against Leggetti, a treacherous mob goon who likes to hurt people with the twin buttefly knives that he carries. Jerry ends up neutralizing the blades by tying Leggetti's hands together with a strip of cloth.
- During the torture scene in Sharky's Machine (1981), a thug played by Dan Inosanto brandishes a balisong to intimidate Sharkey, who only asks if he's auditioning for a job at Benihana's. Then the thug starts using it to cut off Sharkey's fingers.
- Martial artist and stuntman Jeff Imada has written a couple of books on the history and use of the balisong, and puts his talent to use in several movies.
- Big Trouble in Little China opens with Imada doing a balisong/stick routine.
- Nice Dreams has him playing a waiter who uses a balisong to open a bottle of wine.
- In Payback, the Chow's Bodyguard, played by Imada, flips a butterfly knife and prepares to cut Porter before being interrupted by the corrupt cops.
- Imada was stunt co-ordinator for Mission of Justice, which has plenty of balisong usage.
- In Lethal Weapon 4, one of Wah Sing Ku's mooks wields a butterfly knife. Oddly, Jeff Imada plays the other mook.
- Elementary: Sherlock carries a butterfly knife and uses it to cut through a lithograph in "The Leviathan" and dig out a test-fired bullet in "Details". In "M", he adds it to his collection of torture implements, but he doesn't use it. Sherlock's manipulations are simple and competent.
- In the Law & Order episode "Knock Off", Dianne Cary (guest Katee Sackhoff) has a butterfly knife sitting on a shelf open, next to a pair of nunchaku. She became obsessed with martial arts and self-defense after being raped.
- In an early episode of Burn Notice Michael uses one to puncture a tire.
- Episode "Glass Houses" (S1E20), Jaden uses a break in the fight to draw a butterfly knife, but she botches the opening. Nathan shoots Jaden to save Alex.
- In "Pale Fire" (S2E11), a Gogol mook flips a butterfly knife open and slashes Alex, but she traps it and kills him with it.
- In the White Collar third mid-season finale "Countdown", Keller snacks on a mango while threatening Mozzie, cutting pieces off with a butterfly knife. It is locked open and not flipped, which would be difficult to do while coated in juice.
- Charlie in Spin City uses one to carve the description of Caitlin's sex dream into his desk.
- A 1980's made-for-TV movie "Trial of the Incredible Hulk" (the Bixby-Ferrigno version), introduced the character Daredevil. A mook attempts to threaten Daredevil with some noisy balisong flipping, to which The Man Without Fear simply comments "Your knife hurts my ears" before pounding the guy.
- Action-Adventure writer Jerry Ahern is a fan of the weapon, so several of his characters use the balisong (e.g. Natalia Tiemerovna in The Survivalist series and Josh Culhane in The Takers), usually without the fancy opening moves.
- Yakuza assassin Junji "Kappa" Kon in The Man with the Red Tattoo carries a butterfly knife on himself at all times, and puts it on a deadly use on few targets.
- In Pathfinder, a butterfly knife is an exotic light melee weapon, though apart from being a bit more expensive there's no real mechanical difference between a balisong and an ordinary dagger.
- Ace Attorney Investigations has a special variant that converts into a key. It even has a butterfly motif.
- BlazBlue: One of Hazama's/Terumi's iconic weapons is a set of especially vicious-looking curved butterfly knives (the other being his Grappling-Hook Pistol Nox Nyctores, Ouroboros).
- In StarCraft II, Gabriel Tosh flips a butterfly knife during some of his conversations. Since it is computer generated, his manipulations are fast and crisp. If the player picks Nova's mission, she will flip the knife after assassinating him.
- Team Fortress 2's Spy has a butterfly knife as his default melee weapon. It can be used for a relatively weak stab* , or an instant-kill Back Stab.
- Brayko from Alpha Protocol uses a butterfly knife. He flips it during combat when he goes on his cocaine-fueled stabby rampages. After dealing with him, you get it as a souvenir in your safehouse, with Mike noting that there's still enough coke residue on it to get really high.
- In Saints Row 2 a butterfly knife is one of the many melee weapons the protagonist can use.
- Appears as a fairly common weapon in Postal 2 under the name Balisong. Not particularly powerful in a straight fight, but it will kill any civilian (that is, not a soldier, police officer, or Taliban) in a single Back Stab.
- Certain mooks carry them in Hotline Miami 2: Wrong Number. Idle guards can be seen flipping them open and close.
- Mortal Kombat has an odd example; From Mortal Kombat: Deadly Alliance to Mortal Kombat: Armageddon, resident Knife Nut Kano's weapons fighting style was marked as "Butterfly Knives", despite him Dual Wielding what looks more like a pair of Bowie knives. This is due to developer error: the weapons in question are actually known as butterfly swords, meaning the devs made the mistake noted in the description of confusing two unrelated weapons.
- The butterfly knife is one of the best melee weapons in Unturned, and a more durable and faster-to-swing alternative to the military knife. It can only be found in militia encampments and prisons. Unlike the majority of examples, the player never flips it open or closed.
- During the kidnapping in Marilith, the title character draws a butterfly knife from the waistband of her skirt and flips it open between panels.
Marilith: "Oh, I got your hall pass... here in my pants!!"
- Questionable Content: In #2185: "The Sizzler", Faye flips a Benchmade 40TR (trainer, red), including tossing it in an aerial.
- Angelina Jolie has a pair, and demonstrated how to use one on Conan O'Brien's show.
- Plenty of people create youtube videos doing tricks with them. It is quite fun, except there is a risk of cutting yourself. That is where the fake blade variation comes in handy.
- There are butterfly knife combs that actually work as a comb and something to do tricks with. Though if you are not careful it is still metal and will give you small cuts that go through a few layers of skin. That said, it could be used as a weapon in a sticky situation with enough applied pressure.
- Another non-weapon variation is the butterfly knife bottle opener. The more common variety has the wide spoon-shaped end usually seen on bottle openers, and is distrusted as a mere novelty for its lack of balance as a result. A rarer variation is made from a section of metal with bottle opener hooks cut into the side. This version is substantially better balanced and therefore handles trick performance much more easily, but is harder to use in its intended drink-serving function.
- Balisong ink pens are also available.