One way of demonstrating a being's wildness is for them to beat their chest while yelling. This might be combined with a Mighty Roar.
This is most often done by gorillas (killer or otherwise). When a character that is not a gorilla does it, it is usually either to show that he feels as strong and mighty as a gorilla, or that he is as brutish and uncultured as an ape. It also may be Played for Laughs, when it is done by a small and/or weak character.
Two Stock Shout Outs often include chest pounding. One is a literal Shout Out to Tarzan, where the character lets out the ape-man's Signature Roar while beating his chest; the other is "King Kong" Climb, where the creature on top of the building (which is often a King Kong Copy) pounds its chest to recreate the iconic scene from King Kong (1933).
In reality, gorillas may pound their chest for different purposes: as a display of dominance, as a release of stress, to warn neighbouring gorilla groups about their presence, and most notably, it is one of the nine phases of the ritualized fight between Silverbacks. Juvenile gorillas also beat their chest playfully. Also, it is usually inaccurately portrayed in media: real gorillas more often do it with open or cupped hands rather than clenched fists, which produces a sound that's less "thumping" and more "popping."
It might be part of a Victory Pose of a savage, brutish fighter. Compare Stop Hitting Yourself where it's someone else who moved the hands of the victim to hit him/herself, and Macho Masochism, when the character hurts himself in a much more painful way to show off his toughness. Contrast Breast Attack, when a character hits someone else's chest in a fight (usually a woman's as it's more painful to them).
- Dragon Ball Z: The final form of Majin Buu, Kid Buu, does this before his final fight with Goku and Vegeta. Humorously, he continues pounding his chest even as Goku kicks him in the face and sends him flying into a cliff. There's no particular reason for him doing this — he's just completely off his rocker.
- Ape Admin from the TBS version of Aggressive Retsuko does this when she gets upset or excited, as one of the many Furry Reminders the series uses as jokes. Commendably, she explains in one episode that she's using the palms of her hands to do it.
- In Zoids: Chaotic Century, Iron Kong Zoids are sometimes seen pounding their chests before attacking.
- In Pokémon, Norman's Slaking does this over the course of his battle against Ash's Grovyle.
- In Toriko, this is invoked during the Rainbow Fruit arc: as they reach the Biotope where the fruit grows, the heroes hear a loud banging noise, which Toriko correctly interprets as the local "boss of the Biotope", the Troll Kong, beating his chest to intimidate intruders. Toriko simply causes a bigger noise by thumping his own chest as an answer to the Troll Kong's challenge.
- In Kemono Friends Season 2, Western Lowland Gorilla makes her debut appearance pounding her chest to get the attention of her bickering followers. Commendably, she does this with her open hands and palms instead of her fists, and it produces a "popping" sound rather than "thumping".
- Wallace & Gromit: The Curse of the Were-Rabbit: The eponymous beast does this in the forest — while howling like a wolf — which incites all the normal garden bunnies to imitate him.
- In Tarzan, Kerchak does it on two occasions: first when getting enraged about Kala adopting Tarzan, and second when he menaces Jane in the human camp. In a rare case of Shown Their Work, he does it with open hands. Tarzan also does it in the closing shot of the movie (with clenched fists) while letting out his Signature Roar.
- Tarzan is sometimes shown doing this while performing the "Tarzan Yell", as the title character does in Tarzan, the Ape Man (1981), as seen here. This is carried over from the books (see Literature).
- King Kong, being a giant gorilla, does this from time to time; most iconically after defeating the giant reptile (Tyrannosaurus rex / giant snake / V-rex), and when fighting the planes on top of the building.
- Multiple characters do it in in George of the Jungle, including Ape the ape when he pretends that he's an unintelligent, non-talking animal, George as part of his courtship display to Ursula, and a monkey (named Little Monkey) when fending off a lion. See the last one here.
- Dian Fossey does this in Gorillas in the Mist when she imitates the gorillas' behavior to blend in with the group. The scene is a bit of a Fridge Logic, considering that chest-beating often means a display of dominance or a challenge to fight — probably not the best idea when you are trying to earn the trust of a 300-pound silverback.
- Peewee does this (complete with Tarzan Yodel) to celebrate Sex as Rite-of-Passage at the end of Porky's.
- The Jack Benny Program (the TV version): Benny does a very wimpy, pathetic version in a sketch where he plays Tarzan. Jane (played by Guest Star Carol Burnett) fares much better minus the chest pound - her doing the Tarzan yell later became a Running Gag during the audience Q&A segment of The Carol Burnett Show.
- The original script for "Amok Time" on ''Star Trek: The Original Series' had Spock doing this and yelling "Kikki-nee klart!" Nimoy, and fans everywhere, are grateful to D.C. Fontana and Bob Justman for getting rid of that one.
- Hyakujuu Sentai Gaoranger / Power Rangers Wild Force: Gao Gorilla / the Green Gorillazord does this when summoned.
- In Walking with Beasts, when two Australopithecus troops meet and get in a squabble, a few of them beat their chest while screaming at the other troop.
- Wonder Woman: In "Wonder Woman vs Gargantua", Gargantua pounds his chest while being displayed to the public.
- Donkey Kong:
- Variation: The Pokémon move Belly Drum causes the user to damage itself but greatly increases attack.
- The first gorilla enemies in Golden Sun are called chestbeaters for this reason.
- The roar animation of the male draenei in World of Warcraft is like this.
- In XCOM: Enemy Unknown, Mutons and related units (Berserkers and Elites) do this whenever they take damage in an attempt to intimidate the attackers (which can actually induce panic in them). As explained much later by the Big Bad, the "Muton" species is considered savages by their masters, who gave them advanced weaponry and armor solely to serve as Cannon Fodder.
- Barret Wallace of Final Fantasy VII does this when he's worked up.
- The Fomoire folk in Folklore, found in Hellrealm can often be seen doing this in the midst of battle.
- Team Fortress 2:
- The Soldier's taunt with The Direct Hit and the Beggar's Bazooka.
- The Yeti Smash taunt turns the player into a yeti who proceeds to do this.
- In Path of Exile's character select screen, the Marauder occasionally bangs on his own head with his maul.
- Overwatch: Winston's "Primal Rage" intro has him pounding his chest.
- In Bully, Russell often beats his chest while yelling before rushing in for an attack.
- Rask's taunt for Augmented Regeneration in Atlas Reactor.
- In the Battle Clash sequel Metal Combat, Guido shows off his new and improved Garam mk-2 by doing this, instead of the simple muscle flex poses he did in the first game.
- In The Elder Scrolls series, Ogrim are a massive form of lesser Daedra that are as dim-witted as they are strong. They also possess a strong Healing Factor, and in Online, this is how the activate it. If interrupted, it temporarily stuns them.
- Heat does this as his victory animation in Digital Devil Saga.
- Tom and Jerry both do it when caught up in the throes of their latest crush. Usually a variation of Post-Kiss Catatonia. A kiss makes them feel mighty.
- Looney Tunes:
- In Bugs Bunny short "Rebel Rabbit", after the U.S. government puts a bounty of one million dollars on him, Bugs is overjoyed. He calls himself "Bugs Bunny, king of the beasts" and gives out a Tarzan yell while pounding his chest.
- Bugs also thumps his chest in the short "Gorilla My Dreams" when mocking the angry Gruesome Gorilla.
- The gorilla in SpongeBob SquarePants episode "I Had an Accident" likes to do this in-between his beatings of Sandy and Patrick.
- Tarzan does it in the opening credits of The Legend of Tarzan, as well as on various occasions in the show. Other characters such as Kerchak, Tublat, Moyo and even Professor Porter do it too in various episodes (the first three characters are gorillas, and the Professor is pretending that he is Tarzan).
- An old episode of Beavis and Butt-Head has Billy Bob doing this after he breaks through a whole to chase the pair for taking his scooter.
- Candace has a treehouse robot do this while piloting it in the climactic fight of Phineas and Ferb The Movie: Across the 2nd Dimension.
- Buttercup of The Powerpuff Girls does this at one point. While attempting to demonstrate her toughness by taking a hit from an unknown weapon created by Mojo Jojo, she stands in place, yelling and beating her chest while the shot is in flight. Had she not been rescued, she would have been de-powered, as her rescuer noted, was labeled on the weapon.
- My Little Pony: Friendship Is Magic: In episode "Triple Threat", Thorax the changeling shapeshifts into a large bear, and he immediately lets out a roar and pounds his chest — despite this intimidation gesture being more associated with gorillas than bears. Of course, he's neither.
- In an episode of Masha and The Bear, the two title characters come up with possible scripts for a movie. One of them is King Kong with the Bear in the title role, thumping his chest on top of a skyscraper as airplanes fly towards him.
- The traditional New Zealand dance "haka", traditionally performed by Maori warriors and popularized by the rugby team "All Blacks", includes slapping one's chest and yelling.