Used as both a teaching device and a subtle nod to adult viewers, literary references have long been a keystone feature in cartoons. Here are some you might have missed the first time around.

1. JOHNNY BRAVO // CHARLIE AND THE CHOCOLATE FACTORY

In the episode, "Panic in Jerky Town," Johnny Bravo wins a trip to a beef jerky factory. Beef jerky is Johnny’s favorite food and his extensive knowledge of the food product impresses the factory owner, who decides to name him the successor of Jerky Town. After finding his companion’s clothing in the machinery, Johnny mistakenly concludes that the jerky is actually made out of humans and announces it during what would have been his inauguration. He later finds out the secret ingredient is healthy soy, which is a nod to the movie, Soylent Green.

Watch it: DailyMotion

2. LOONEY TUNES // DR. JEKYLL AND MR. HYDE

In its original, near-40-year run, Looney Tunes covered a lot of ground. The classic cartoon parodied everything from Richard Wagner's opera Der Ring des Nibelungen to Vincent Price. Even Bugs Bunny himself is partly based on Clark Gable’s character in It Happened One Night (1934). The episode “Hyde and Hare,” which aired in 1955, turns its sights on Dr. Jekyll and Mr. Hyde. The plot of the cartoon uses the basic gist of the book (doctor drinks a potion and becomes a monster), but uses it for comedic purpose. Bugs Bunny convinces a kindly doctor to bring him home, only to discover he drank a potion that turns him into a green-skinned, red-eyed monster.

After some hijinks, Bugs and the doctor decide to dump out the rest of the potion. When they discover the vial is empty, the doctor accuses Bugs of drinking it. Bugs leaves, insulted, only to turn into a monstrous rabbit as he walks away.

Watch it: DailyMotion

3. THE GRIM ADVENTURES OF BILLY AND MANDY // HARRY POTTER

For the first episode of the second season of The Grim Adventures of Billy and Mandy, the show decided to blend the plots of Harry Potter and Animal House. The result is a fun episode called “Toadblatt's School of Sorcery.” In it, the titular characters enter a wizard’s school that closely resembles Hogwarts with some comical differences—the Sorting Hat is now a Squid Hat, the potions class also teaches Spanish, and Harry Potter is depicted as the geeky Nigel Planter. Each of the houses is treated like a competitive frat house, with one particular house considered the ire of the frog dean, reminiscent of Animal House.

Watch it: YouTube

4. STEVEN UNIVERSE // A WRINKLE IN TIME

Cartoon Network’s Steven Universe bears many similarities to Madeleine L'Engle's iconic science fiction novel, A Wrinkle in Time. As Tumblr user leeshajoy points out, the character Connie can be seen holding a copy of the book in the intro. There have also been a lot of convincing parallels between the book and the show: Both have a shy but intelligent female character and a social but misfit male character that have some romantic tension. The two team up with three supernatural beings that look like human women to fight against an alien world that values conformity. The show’s creator, Rebecca Sugar, has not gone on record to confirm or deny that the show is based on L'Engle's work, but Connie’s book has since changed to another science fiction novel—likely Ursula K. Le Guin's The Left Hand of Darkness.

Watch it: Amazon

5. RUGRATS // THE GREATEST GIFT

You might better know Philip Van Doren Stern's short story The Greatest Gift better for the movie it inspired: It’s a Wonderful Life. The movie has been subject to many parodies and spoofs over the years, including one by Rugrats. In the episode “Chuckie’s Wonderful Life,” the audience gets to see what life would be like without the gentlest Rugrat—and it turns out things would be pretty grim. A quick fly through town with Chuckie’s “gardening angel” shows that all the characters are in trouble without a moral compass: Phil and Lil become destructive monsters while their parents huddle in the corner, Tommy becomes homeless, and Angelica forces Tommy’s parents to continuously feed her cookies. Meanwhile, Chuckie’s dad becomes a hermit with only a sock puppet for company. By the end of the episode, Chuckie—clearly as disturbed by the scenes as the audience—learns his place among his friends and family and happily returns home.

Watch it: Amazon

6. PINKY AND THE BRAIN // AROUND THE WORLD IN EIGHTY DAYS

In the Pinky and the Brain episode, “Around The World In 80 Narfs,” the title characters set out to become world travelers. Because the episode takes place in 19th century England, The Brain assumes that the quickest way to take over the world is to become Prime Minister, and the easiest way to do that is to first become the president of an explorer’s club, which is how they end up attempting to circle the world in less than 80 days. The ill-fated trip leaves the mice stuck in a horse and buggy and unable to claim the presidency, leading to their usual phrase, "What are we going to do tomorrow night?"

Watch it: Amazon

7. THE SIMPSONS // LORD OF THE FLIES

The Simpsons have parodied a ton of classic literature, including Flowers for Algernon, The Shining, and The Crucible. Perhaps one of their best known parodies is “Das Bus,” which mirrors the story of Lord of the Flies. After a bus accident, a group of Springfield students are left stranded on an island. Bart takes on the character Ralph by blowing into a conch shell and asserting himself as the leader. The kids survive on snack food retrieved from the bus until waking up to find the remainder of it gone. Milhouse—who is possibly The Simpsons's version of Piggy—is blamed thanks to his nacho breath and large stomach.

After a trial by Bart and Lisa deems him innocent, the other children attempt to murder Milhouse and chase him into a cave where they find a boar with a bag of chips on his tusk. Milhouse is declared innocent and the stranded children decide to kill and eat the boar.

Watch it: Simpsons World

8. PHINEAS AND FERB // MOBY DICK

In “The Belly of the Beast,” the Disney show decides to take on the iconic tale of Moby Dick—with just a dash of Jonah and the Whale. In Danville, the town celebrates Harbor Day, where they reenact a story of a shark that terrorized the town before being driven out by the townspeople. While watching preparations, Phineas and Ferb decide they want to build a better and more advanced shark for the event. Candace sees the mechanical shark being lowered into the water and decides to chase after it to prove to her parents that her brothers were up to no good. She—along with her friend and an Ahab-like boat captain—pursue the shark. Eventually the captain gets eaten by the robotic shark, who is confused about why the interior doesn’t look more “insidey.”

As Candace continues to chase after the shark, it becomes clear that her impossible mission to bust her brothers mirrors Ahab’s futile desire to seek revenge on an animal. Just as she’s about to expose her brothers, a vat of taffy explodes and Candace is once again left empty-handed.

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9. SPONGEBOB SQUAREPANTS // 1984

In the episode “Back to the Past,” SpongeBob and Patrick accidentally alter their timeline using Mermaid Man’s time machine. The future looks a lot like George Orwell’s idea of it in 1984. Mermaid Man’s nemesis, Man Ray, has taken over with a number of posters that resemble the Big Brother signs, stating “He's Watching You."

Watch it: Amazon

10. DEXTER’S LABORATORY // THE MOST DANGEROUS GAME

When Dexter’s Laboratory wasn’t following around the boy genius, it was showing us the heroic escapades of The Justice Friends and Dexter’s pet monkey. In “Dial M for Monkey,” the secret superhero is kidnapped by a lion-like alien named Huntor. Similar to the hunter in Richard Connell's The Most Dangerous Game, Huntor has grown bored of his usual game and is looking for a challenge. After stripping Monkey of his powers, he’s dropped in a game preserve. Using guerilla tactics, Monkey manages to destroy the preserve and get away. Huntor also makes a small appearance in Samurai Jack with a now robotic elephant.

Watch it: YouTube

BONUS: RICK AND MORTY // NEEDFUL THINGS

As an adult-geared show, Rick and Morty isn't from anyone’s childhood. Still, it’s worth mentioning the episode “Something Ricked This Ways Comes,” which is a fun spin on Stephen King’s Needful Things. The episode plays out a little differently than the book, thanks to its self-aware characters, who quickly realize the nefarious shopkeeper is the devil. In the book, the town devolves into chaos, but in the show, Rick and Summer get ripped and beat up the shopkeeper.

Watch it: Amazon