Walt Disney once said, "Growing old is inevitable, but growing up is optional." The idea of entertaining the inner child is one that has floated around for decades, but it's also been a gold mine for the movie industry, especially for comedic purposes. No matter who plays the role, there's always something funny about seeing established adult actors behave like rowdy kids.

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Scenes of adults letting go of their pride and dignity to do something childish are fertile ground for comedic possibilities, whether that's engaging in some grade-school-level activity or simply getting into a loud squabble over something silly. The fact that no one is immune to letting the kid inside them out to play never fails to display both a hilarious and human element that connects with the audience.

Carnage (2011)

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John C Reilly, Jodie Foster, Christoph Waltz, and Kate Winslet all star in Carnage

Based on the play God of Carnage by Yazmina Reza, this dark comedy movie features a star-studded cast portraying two pairs of parents who try to come to a cordial situation after their children end up in a violent fight. But as tempers rise between the four adults, their masks of civility start to slip and a polite negotiation in an apartment soon turns into a playground brawl.

The script itself is a serving of dark absurdist humor by itself, but the film goes a step beyond by incorporating Oscar-winning and Oscar-nominated actors in its cast. While the stylings of John C. Reily certainly include some childish actions, to see decorated actors like Christoph Waltz, Kate Winslet, and Jodie Foster screaming, squalling, and fighting like ten-year-olds is ingeniously funny.

Big Bully (1996)

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Rick Moranis and Tom Arnold in Big Bully

In many movies, old grudges make even the most adjusted and established people do wild things. Big Bully casts Rick Moranis and Tom Arnold as two former schoolmates who become locked in an old cycle when the nerdy David runs into his former antagonist, Roscoe "The Fang," 26 years later. Needless to say, the results are packed with as much tension as they are comedy.

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Similar to movies like You Againthe film plays with the idea of digging up the past. Although both parties involved are mature adults with jobs, families, and so on, a schoolyard feud causes them to forget the years that passed between them and revert back to a childish state. Thankfully, the past is buried and the two walk away as new friends instead of enemies again.

The Benchwarmers (2006)

Stream on HBO Max

David Spade, Jon Heder, and Rob Schneider all star in The Benchwarmers

Keeping with the theme of bullies and nerdsThe Benchwarmers follows a trio of geeky adults with a love for baseball who never got picked to play as kids. After watching a group of kids get bullied off of a baseball field, the three friends take on local little-league teams to win newfound respect, an elaborate baseball stadium, and the overdue opportunity to play.

Baseball themes and motifs aside, the biggest selling point is the performances from the film's main cast. Jon Herder, Rob Schnieder, and David Spade are absolutely hysterical as the titular Benchwarmers, each bringing a different flavor of nerd to the table. Essentially behaving like grade-school kids in bigger bodies, the three capture the roles well and act as the film's lovable underdogs.

Grown Ups (2010)

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The cast of Grownups featured on their poster art

Adam Sandler is definitely one actor in Hollywood who knows how to unleash his inner kid. The man has practically built his career on over-the-top roles where he throws all maturity out the window, but it's when he teams up with his friends Kevin James, David Spade, Chris Rock, and Dan Schnieder that he truly unleashes the madness.

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The Grown Ups movies feature a group of high school friends reuniting after their lives pull them apart from one another. While they revert to their high school mentalities, the humor is more heartwarming than humiliating at times. That being said, watching the leads behave like their cocky, and at times dumb, high-schooler selves is always full of gut-busting humor.

Billy Madison (1995)

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Adam Sandler screaming in Billy Madison

Before he was out on the lake with his buddies or trying to steal uncut gems, Sandler went back to school in his production of Billy MadisonIn order to save his father's fortune 500 company, his childish son must complete the 12 years of school he missed to prove his competence to run the business. Naturally, watching Sandler behave like a kid in grades K-12 is the crux of the production.

As the titular Billy Madison, Sandler sticks out amongst the grade-schoolers like a sore thumb, but equally matches their energy (and lack of maturity) to a tremendous degree. Plus, the fun clearly had by both Sandler and his younger peers is clearly present on the screen.

Step Brothers (2008)

Stream on Peacock

Will Ferrell and John C. Reily pose on the poster for Step Brothers

The term "man-child" is a great descriptor for Will Ferrell and John C. Reily's characters in this cult classic. Watching grown men behaving like Brennan and Dale is equal parts comedic and cringe as the two 40-year-olds behave like they're still in elementary school, complete with their favorite toys, treehouse, and infamous homemade bunkbed.

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The film is practically a staple of the comedy genre, armed to the teeth with its numerous funny scenes, quotes, sequences, and recognizable set pieces. By little exaggeration, the words "Catalina Wine Mixer" will never be the same for movie-goers again.

Toys (1992)

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Robin Williams plays Leslie Zevo in Toys

When a character owns a successful toy company, a certain amount of childishness is not only expected but required. Case in point, Robin Williams as Leslie Zevo in Toys. Williams was never one to shy away from his childish side, and his portrayal of the eccentric toymaker perfectly complements his profession and personality.

A sort of coming-of-age comedy but for an adult, the plot concerns a brilliant but childish toymaker who must save his father's company from his military uncle who wants to use the factory to make war games and violent army-based toys. Williams delivers an on-point performance with more than enough childish delight, even after Leslie has to take his place at the head of the company.

Hook (1991)

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Peter Pan smiling in Hook

Characters don't get more childlike than Peter Pan, and once more, Robin Williams steps up to the plate with his patented eccentricities and over-the-top personality to play an adult version of "the boy who never grew up." As contradictory as that might sound, William's performance after the transition from Peter Banning to Peter Pan truly sets his inner child free.

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When Peter finds his happy thoughts, Pan is truly unleashed and his joy and delight are positively palpable. Williams only highlights the portrayal with his fits of laughter and manic energy, giving a the audience a  joyous and soaring version of the character no one will forget.

Mary Poppins (1964)

Stream on Disney+

Mary Poppins and Bert smiling in Mary Poppins

Disney is a pro when it comes to feeding an audience's inner child, and the studio has released a handful of movies with adults behaving like children, for better or worse. But easily one of the most successful films to adapt this principle has to be Walt's Magnum Opus, Mary Poppins. It's an overload of whimsy and magic that even the most stoic of viewers can enjoy, and it can make anyone's childish side come out to play.

Uncle Albert has tea parties on the ceiling, an onslaught of chimney sweeps dance on the rooftops, Dick Van Dyke dances with animated penguins in one of Dick Van Dyke's best movies, and a group of elderly bankers leaves their bank to go fly a kite, the list goes on. Call it Disney magic or Mary Poppins working her classic charm, but it definitely continues to enchant and delight viewers of all ages.

Pee-Wee’s Big Adventure (1985)

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Pee-wee riding his bike in Pee Wee's Big Adventure

If there's one character who has built an entire existence on maintaining a childish persona, it's Pee-Wee Herman. Paul Rueben's iconic character is practically a living cartoon character, and all his eccentricities add up to a brilliantly comic manifestation of childish delight that can't be denied.

In his original film debut, Pee-Wee deals with all the childish cliches, such as his large collection of toys, favorite sugary breakfast cereal, fear of clowns, and his beloved and garish bicycle. His titular adventure takes him on a cross-country journey, putting him in various wild and weird predicaments that he's able to escape by his childish nature alone. Sometimes, being an adult can get in the way of a fun adventure.

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