Slang refers to terms that are commonly used in everyday language but not considered official words, including exclamations and non-traditional insults. Slang can be positive or negative, and some terms carry connotations of both, depending on the context in which they are used.
- Bleeding hog monkeys – An expletive used by the pirate captain when he sees Team Avatar abscond with his ship. A varied form of "flying hog monkeys".
- Flying fire ferrets – A phrase used by Satoru when struck with an idea. Comparable with "egad!" or "eureka" in context.
- Flying hog monkeys – A phrase used by many members of Team Avatar in unpleasant or unlucky situations.
- For Yangchen's sake – A phrase used by Earth Kingdom people to express annoyance or impatience.
- In the name of Oma's bastard children – A phrase used to express annoyance.
- Monkey feathers – An obscenity used by Aang when events are not favorable. Variations include "double monkey feathers" and "monkey feathers on top of monkey feathers".
Insults in the World of Avatar often take the form of derogatory names for members of the various nations or reference personal qualities that set the target apart. This is not universal, however, and some insults simply express annoyance at another person's actions.
- Ash maker – An insult used by the Freedom Fighters in reference to the citizens of the Fire Nation, even those with mixed Fire Nation-Earth Kingdom heritage, such as Kori Morishita.
- Blockhead – An insult intended to imply stupidity - see also meat head. It was used by Toph to describe Bolin's inability to learn metalbending.
- Blowhard – A term used by Sokka to describe a boring professor.
- Bozo – An insult used by Katara when battling the Rough Rhinos.
- Chattering hog-monkey – Used to indicate excessive or unnecessary talking. Katara called Sokka this when he kept shouting unneeded waterbending advice at her.
- Colony trash – An insult directed at Fire Nation colonists who live in the Earth Kingdom. It was used by Hide to insult Aang, who had enrolled under the alias of a Fire Nation colonial in a school on the mainland.
- Dirt people – A Fire Nation insult directed at people with Earth Kingdom heritage, especially earthbenders. It was used by Master Kunyo to insult Toph Beifong, and, later on, in an official complaint issued by him.
- Dunderhead – A mild insult used by Aang when referring to Toph's stubborn nature. Synonymous with less rude insults such as "idiot" and "stupid-head". Toph herself used this term to refer to Master Yu and Xin Fu after she escaped their metal prison.
- Fancy fingers – A pejorative term for someone who is overly refined. When Toph claimed that Team Avatar does not have the manners to blend in with the upper class of Ba Sing Se, Katara fired back that Toph was not exactly "lady fancy fingers".
- Fatso – A derogatory term usually reserved for overweight people. Used by Azula when referring to her uncle Iroh as "Uncle Fatso".
- Fire tosser – A term used during the era of Raava to refer to those with control over the element of fire, predating the term firebender. It was used by the aye-aye spirit to describe a group of men who had departed from their lion turtle and were behaving disrespectfully toward nature and violent to the spirits with whom they came into contact.
- Gasbag – A word used to refer to someone who talks too much. Zuko described his uncle, Iroh, and an Order of the White Lotus member as such when they were talking to one another and Zuko could not discern the meaning of their conversation.
- Gumflapper – A similar term to "gasbag", this word was used by Toph when referring to Bolin after he would not stop talking.
- Hoodlum – A pejorative term referring to someone who generally flouts the law. Korra referred to a waterbending member of the Triple Threat Triad as a hoodlum when she saw them extorting money from a shopkeeper.
- Jerkbending – A term used by Sokka as a synonym for firebending to express his dislike for the bending art.
- Lily livers – An insult used by Toph on her metalbending students. It is the equivalent of "yellow-bellied".
- Loudmouth – An insult used by Toph to describe Sokka's openness about killing the Fire Lord during their visit to the Fire Nation fishing village, Jang Hui.
- Meat head – An insult used to imply someone's stupidity. It was used by Katara to refer to Aang and Sokka who wished to take the easy way out of a situation.
- Northie – A derogatory term that refers to citizens of the Northern Water Tribe. During the Water Tribe Civil War, Northie was used in Southern propaganda, such as in the Nuktuk theme song.
- Nut brained – An insult with the equivalent of "stupid". Katara used it while yelling at her brother.
- One trick poodle pony – A person or thing that is limited to a single skill. Bolin stated to Korra and Mako that Pabu was "not just a one trick poodle pony" after the latter chewed through the ropes tying up the Future Industries Fire Ferrets. It is the equivalent of "one trick pony".
- Rinky-dink town – A term used by Sokka to refer to towns in need.
- Shut your airhole – The equivalent of "shut your mouth" or "shut up".
- Snow savages – A Fire Nation insult directed at Water Tribe members. It was used by Master Kunyo to describe Sokka in an official complaint.
- Weasel snake – A term used to refer to someone who is conniving and manipulative, often doing so with selfish motivations.
- Dancy Pants – A term used by Toph to refer to Aang's dancing.
- Earthiness – A term used by Aang to refer to Earth King Kuei. It is the equivalent of "majesty".
- Fieriness – A form of Earthiness used by Aang to refer to Fire Lord Zuko.
- Hotman – A term for someone from the Fire Nation or the equivalent of "sir". Aang used this term to address strangers until he realized it was drawing attention, the generic term having become outdated by 100 AG. He later called Zuko "Sifu Hotman", much to the firebender's dismay.
- Kingliness – A term used by Sokka to refer to Earth King Kuei. Like earthiness, it is the equivalent of "majesty".
- Snoozles – A term used to refer to someone who is either sleepy or still asleep. It was used by Toph to describe Sokka when he complained that her and Aang's earthbending training was depriving him of further sleep.
- Sugar Queen – Another slang term used by Toph. Depending on the tone in which it is said, its meaning varies from an insult to a term of endearment with a mildly mocking connotation. Usually it means "goodie-two-shoes" or "know it all". A variation is "sweetness".
- Sweet sugar cakes – Similar to the word "babe", it was used by Ty Lee to address Azula during Chan's party while teaching the princess how to get boys to like her.
- Twinkle Toes/Fancy Dancer – Terms used by Toph to describe Aang being light on his feet.
- Bite us in the blubber – A term used to indicate that a specific action will have consequences later on, or the equivalent of "come back to haunt us". Sokka said this to Aang when the Avatar rudely told Joo Dee off.
- Bust his [her] chops - A term for nagging someone (playfully or otherwise) about an issue they'd rather not discuss. Bumi mentioned in a letter to Korra that he tried not to bust Tenzin's chops too much.
- Elephant-rhino in the room – Used to refer to an important issue, but one that people would rather not discuss. The equivalent of "elephant in the room".
- Flameo – A term that has several definitions, depending on the context, including "hello", "goodbye", and "great". It was used by Aang while attending a Fire Nation school, much to the confusion and amusement of others. Used before the Hundred Year War, the term had fallen out of everyday use by 100 AG, but it eventually resurfaced, though by 171 AG, the meaning had changed to be that of a mild swear, used to convey surprise and shock.
- Glow it up – A phrase used to refer to going into the Avatar State.
- Hullabaloo – A term used by Aang's music teacher at the Fire Nation school to refer to Aang's dancing while playing the tsungi horn.
- Legit – Short for "legitimate".
- Oogies – A term equivalent to "yuck" or "gross". It was frequently used by Sokka in the events surrounding the Harmony Restoration Movement in reference to Aang and Katara's romance. Toph compared it to licking someone's hand.
- Polar bear doghouse – A term used to indicate someone is in trouble with another person, with the implication being that they must be forgiven in order to leave said place. It was used by Opal to tell Bolin that she had forgiven him after his involvement with Kuvira's army put a strain on their relationship.
- Sitting turtle duck – The equivalent of being a "sitting duck". Bolin used this term to refer to Korra's flat-footed stance while teaching her the pro-bending style of earthbending.
- Stay flaming – The equivalent of "stay cool" in the Fire Nation. Used primarily before the Hundred Year War, it was outdated by 100 AG.
- Working my arrow off – A phrase of Air Nomad origin, it refers to the airbending master tattoos and means to work hard; Aang used it to indicate to Sokka that he had been training very hard, and thus deserved some time off.
- Yip yip – A term equivalent to "go" or "giddy up". It is used to command a flying bison to fly.