You are a Ninja. What's this? You don't have a Katana? Fine, then you may get the second most popular ninja weapon: Nunchaku.
Nunchucks, like the katana, are the Japanese weaponization of the Rule of Cool. All ninjas that don't use swords use chucks and anyone that knows karate knows how to use them. They are even so easy to make that you can just chain two things together and make Instant Chucks. Unfortunately, nunchucks are to katana as the Luigi is to Mario, Badass on its own but is never given the lime light.
The Nunchaku are a popular martial arts weapon developed from the rice flail in China, Okinawa, and possibly other places in the Far East, consisting of two hard sticks of wood or metal joined together by a cord or chain. In addition to being used for powerful strikes, the cord can also be used for strangling enemies. A three-stick variant of this weapon exists called the three-sectional staff (sansetsukon in Japan and san jie gun in China), which is primarily used in Chinese kung fu.
Often wielded by the Bruce Lee Clone. As such, in comedic series, expect anyone wielding nunchuks to make lots of Funny Bruce Lee Noises, just before their inevitable failure.
It should also be noted that ninja never actually used nunchucks. Since they were spies more than warriors, when they had to fight someone, they normally had to kill their opponent quickly and effectively, and nunchuks were definitely not up for that kind of job. It was more a weapon used by farmers and peasants to defend themselves from attackers, since they were easy to make, they could be mistaken by farmers' tools at first glance, and don't require such a high level of skill to use effectively. Or at least to use without hurting oneself permanently.
For a greater variety of flail weapons, see Epic Flail.
This trope is not about fighting with a pair of shoes, by the way (although you certainly could make some nunchuks with some Chucks...). Nor is it about fighting with a certain Nintendo peripheral called a Nunchuck. Although those things do hurt if you let go by accident while it's hooked to the remote...
This trope is also not about multiple Chuck Norris's,because the universe is only big enough for one Chuck Norris,and he's more than a match for anyone on the planet.
Might Gai of Naruto used nunchaku against a clone of Kisame at one point and again during the climactic fight against Tobi.
Bleach: Ikkaku's zanpakutou initially looks like a spear when it's released. However, this simply disguises the fact that it's really a three-sectioned staff. Justified in that Ikkaku's themes are based on Chinese warrior monks, so his weapon (in all its forms) is based on weapons associated with Chinese warrior monks instead of being based on Japanese versions.
Kenshiro of Fist of the North Star, though he is most known for his deadly fists and feet, has used nunchaku on at least one occasion, most notably to deflect thrown knives back at the goons of a whip-wielding minion of God's Army in Episode 6.
Dashiel "Dash" Bad Horse from Scalped uses nunchaku to beat up the hoods on the Rez.
Hawkeye, while renowned as the world's best archer and marksman, is also adept at using Nunchakus, and used them extensively and almost exclusively when he assumed the Ronin identity. Most other characters who have taken the Ronin mantle have used Nunchakus as well.
Discussed in Napoleon Dynamite, which gives us the page quote. His mad skills are never shown, but his pronunciation of the weapon as "numchucks" gives a pretty solid indicator of his actual proficiency.
Undercover Brother. The title character knows how to use nunchucks as part of his martial artist skills. He also hits himself in the nuts while using them during his fight with Mr. Feather.
Dreamscape. When Tommy Ray enters the President's dream in order to assassinate him, he dresses as a ninja and uses nunchucks.
In the 2011 The Green Hornet, Britt Reid insists that Kato must have nunchucks. Kato seems reluctant at first, but does use them quite effectively in the climactic battle.
In the first movie, during the siege of April's apartment, one Foot Clan guy shows off with his nunchaku, prompting Mikey to go "Ah, a fellow chucker, eh?" before proceeding to have a show-off match with him which Mikey handily wins.
In the second movie, Mikey uses two sets of coldcuts as makeshift nunchaku to scare off the last of the robber mooks during the first fight.
Although never used for fighting, the main character of Sidekicks learns to use nunchaku and uses them for an impressive kata near the end of the film. After a training montage involving Amusing Injuries as he keeps hitting himself while practicing.
In Shanghai Noon, one of the Chinese Royal Guards fights with the three section staff version in the final battle. Chon manages to take it away from him and use it against him.
They Call Me Bruce. Bruce carries one but doesn't know how to use it properly so has to talk his way out when confronted by some gang punks. When two police officers see the chucks and threaten to arrest Bruce, pretends they're his chopsticks. And during a Bar Brawl, an FBI Action Girl transforms into a gal wielding a three-stick flail version.
In the rather odd future of The Diamond Age, nunchucks are one of the choice weapons of the gangs in Hong Kong; Nell uses her brother's pair to break the leg of a molester after they run away.
Also by Timothy Zahn, in the Quadrail Series nunchaku form part of one successful attempt to get around the Quadrail's ban on taking weapons on board. The Bellido race routinely carry guns as part of their culture, and on the Quadrail carry harmless plastic copies instead. But the plastic guns can be filled with water and strung on lanyards to make quite effective nunchaku.
In Bruce Sterling's The Artificial Kid, the eponymous protagonist uses a set of nunchaku in his televised battles that included a holdout pistol in the base of each stick.
The hideously-beweaponed Special Constable Andy "Two Swords" Hancock, in the Discworld novels Thud! and Snuff, carries an Agatean weapon that he calls "numknuts", and that Commander Vimes thinks of as two truncheons fastened together. In untrained hands the most likely effect is to hit your own ear.
Live Action TV
In the Babylon 5 episode "Messages From Earth," Ranger Marcus Cole defeats a group of bad guys that includes a nunchuck wielder. Done, perhaps, to show that the Anla-shok are truly Badass.
Nunchaku can be used as weapons in Dungeons & Dragons but there's no real advantage to them other than Rule of Cool- as exotic weapons only monks have the natural proficiency to use them and most monks will prefer to be fighting with their bare hands anyway. At least the other exotic monk weapons such as the kama or siangham do slashing or piercing damage.
In GURPS, the nunchaku has a number of attractive benefits: it's lightweight, cheap, deals decent damage, and is somewhat difficult to Parry/Block. However, they are difficult to master (the Flail Skill is Hard), and can't be used to defend immediately following an attack (unless a Defensive Attack is made).
Ryu of Ninja Gaiden can buy and use a pair of Nunchucks. He can pick up a modified version later: Nunchucks with small scythe blades on the ends.
In Final Fantasy I, the Monk can use five weapons (in descending power level): his fists, iron nunchucks, iron staff, wooden nunchucks, and wooden staff. The Ninja can also use the nunchucks, but by the time you get a ninja, he'll have vastly superior weapons anyway.
Selphie in Final Fantasy VIII uses nunchucks with ridiculously long handles. Her upgraded ones feature mace heads.
Maxi of the Soul Calibur series uses chucks, as did his predecessor and mentor Li Long from Soul Edge. In games and versions where nunchaku are banned, these are replaced by a sansetsukon. The third stick apparently makes it a-ok by the law.
Freyjadour, the hero of Suikoden V, uses an ornamental sansetsukon that (unlike real-life ones) can transform into a one-piece staff. Roy, in keeping with his role as the hero's Body Double, wields an exact copy of it.
As does Nanami in Suikoden II, though hers is a more realistic depiction.
Zero The Kamikaze Squirrel uses a nunchuck. It's quite powerful, but short ranged, and it's the only way to attack the final boss during one of his phases.
In Tekken 5, nunchuks are a costume item for Marshall Law. He gets to finally use one during a fight in Tekken 6 and Tag 2.
Jon Talbain /Gallon from Darkstalkers pulls some nunchucks straght out of Hammerspace in some special attacks, probably to emphasize his training in the martial arts.
In Wizardry8, nunchaku are weapons available relatively early on for use by the "eastern" classes (monk, samurai, and ninja). While they're short range, and all three classes tend to eventually specialize in other areas (unarmed/staves, swords, and thrown weapons, respectively), nunchaku make for decent early weapons with their relatively high chance of knocking enemies unconscious.
Sheila of At Arm's Length prefers to use four sets of nunchucks when facing close quarter threats.
Mikey, again (the 2003 toon incarnation provides the page image). Though in the original cartoon, he was resorting to alternatives like tonfas and a grappling hook in the last seasons (probably because nunchucks are forbidden in some countries). In the 2012 series, he can convert his nunchucks into a kusarigama.
The Transformers Animated incarnation of Jazz is a cyber-ninja (who learned from the same master as Prowl) and uses "laser-nunchaku" in battle.