- Absurdly Sharp Blade: Finn's second sword.
- The family sword that the duo's father created from demon blood can cut through diamond. By the end of "Dad's Dungeon", it becomes Finn's third sword.
- Aborted Arc: The whole "Bubblegum now a child" thing. They patched it up pretty quickly due to the concept not working for the writers.
- Action Girl: Fionna.
- Adipose Rex: Subverted with the Ice King. He appears fat with his robes on, but in "What is Life?", he is revealed to be very skinny, but with an abnormally large chest.
- The Adjectival Man: The... "Magic Maaaaaan!"
- Adorkable: Fionna in the genderswapped episode.
- Aerith and Bob: Played with. Either you have a noble title (Ice King, Duke of Nuts, Princess Bubblegum, Marceline the Vampire Queen, and many more) or you're Billy, Jake, Bob, and so on. Played straight with Lady Rainicorn (where "Lady" is ambiguously presented as a name and a title at different times) and her parents, Ethel and Bob.
- The episode "Go With Me" revealed Princess Bubblegum's first name to be Bonnibel, thus presenting a strange one-woman case: she went from "Betty" in the old pre-release publication to the more whimsical "Bonnibel" in the series.
- The two warring factions in "Paper Pete" are the Secret Guardians of the Library and the Moldos. The Guardian leader's name is Pete and the Moldo leader is Mildwin.
- An Aesop: Often played completely straight, albeit in weird ways. For example, Finn is taught not to break promises by being punished by the Gumball Guardians.
- Affably Evil: The Whywolves from "Donny" are able to alternate between destructive beasts and eloquent geniuses in the blink of an eye.
- Marceline's dad really loves his job... And his job just happens to be being the Lord of All Evil
"Stompin' on ants. Stealing their souls. Stomping on ants. Soul, soul, soul."
- After the End: According to Pen, all of the main characters are living in a post-apocalyptic world caused by "The Great Mushroom War", which is referenced subtly in various ways (abandoned subway stations, nuclear bunkers, a hole blown out of the Earth, etc). Plus, Jake mentions it in "Videomakers". Pen did it because it's cool.
- Lampshaded with the bomb at the very start of the title sequence.
- Marceline's (thousand years ago) childhood is set just after the war, with the burning cities of man in the background.
- "Holly Jolly Secrets" provides evidence that Ice King lived before and through the war, using the crown as protection.
Simon: [The visions] tell me the secrets of the ice and snow. That the power of the crown will save me with its frost. I don't yet know what this means.
- All There in the Manual: Pen's Formspring account occasionally gave away future developments and semi-frequently fleshed out the backstory of various characters. The same goes for the production blog; for example, it's why we know that dress of Marceline's in "Henchman" is made of whywolf.
- Thanks to the production blog, we know that the race of Fish People that appears in "Susan Strong" is known as "hyoomans".
- Alliterative Family: Jake's brother is named Jermaine and his father is named Joshua. Plus, Pen has played with the idea of giving Jake a sister named Jessica. Jake's mother's name is Margaret, though.
- Alternate Continuity: The Adventure Time comics are set in their own continuity and don't factor into the show, according to Word of God.
- Altum Videtur: "Morituri Te Salutamus" ("We who are about to die salute you") is this trope incarnate. There are many Latin phrases like "Et tu?" ("And you?") and "Eludere!" ("Parry!")
- Also, the incantation for banishing/releasing Marceline's dad to/from the Nightosphere is "Maloso vobiscum et cum spiritum", which is roughly "evil be with you and with your spirit" in Latin.
- "Incendium" means "fire" or "burning" in Latin.
- Amazing Technicolor Population: Applies to a lot of the characters. For example, all the Marauders are a shade of blue, the cobbler is green, and Billy is grey. Justified; none of these people are human.
- Ambidextrous Sprite: Obvious with Finn's sword. Hilariously, other characters don't seem to be afflicted with this.
- Ambiguous Gender: Gunter. Not even the crew is sure of whether... it's male or female.
Jake: Gunter's a WOMAN?!?
- Of course, none of this is helped by the fact that the Ice King seems to have named named every penguin Gunter.
- Ambiguously Evil: Ricardio at first.
- Ambiguously Gay: Abracadaniel at first. He didn't want to kiss Princess Bubblegum, and he says, given the opportunity, he would "turn and push". He would even rather die than kiss her. "I'm going back to my cave to wait for someone to kill me." There are numerous more pieces of evidence like turning a wizard pink and turning Ice King's weapon into a butterfly. The cherry on the sundae? He basically has the power over rainbows. He eventually does change his mind about kissing PB, though.
- Ambiguously Human: Pretty much every apparently human character in the show aside from Finn, to the point that 'Finn the Human' is his actual title. The only exception is Susan Strong, and even she isn't confirmed to be one, though it's pretty strongly suggested.
- Ambiguously Jewish: Jake, whose picture in the Xmas special suggests this.
- Ancestral Weapon: Joshua, Finn's and Jake father, possessed a sword created from solidified demon blood. He promised in a series of holotapes that if the two completed a dungeon, it was theirs to keep. And so, Finn slew the giant one-eyed monster guarding the sword, making it his third sword.
- Amulet of Concentrated Awesome: The ice crown for the Ice King. ...And the crystal apple for Tree Trunks. Not to mention Marcie's family's badge of office.
- Amusing Injuries: Subverted more often than not. When someone gets beaten up, it's treated quite seriously.
- Anchored Ship: Finn and Princess Bubblegum.
- As of "Incendium" and its sequel "Hot to the Touch", Finn and Flame Princess.
- And I Must Scream: For some reason, Bubblegum keeps a potion that will "paralyze you FOREVER!" lying around.
- And Now You Must Marry Me: In pretty much every episode involving the Ice King.
- And the Adventure Continues...: Right from the very first short. "Look, Jake! Some ninjas are stealing that old man's diamonds!"
- LSP gets a bout of this in "Trouble in Lumpy Space" when she talks to her parents.
- Lemongrab has a real problem with this.
- Animate Inanimate Object: Finn does this a lot, like say with a sandwich in "Another Way", but the crowner episode is "What is Life?"
- Animation Bump: There are splashes of this here and there. Special mention goes to Jake's dance in "Power Animal".
- Another Dimension: Lots of these.
- Lumpy space: What the lumps?
- The Land of the Dead: c.f. Peppermint Butler.
- The Nightosphere: Marcie's family.
- Anthropomorphic Food: The denizens of the Candy Kingdom and the Duchy of Nuts.
- Anti-Anti-Christ: In the episode with Marceline's dad, it's implied she is this.
- Apocalypse How: The Great Mushroom War (Class 3A), though this is mainly guessing. There is certainly a lot of evidence of a Post Nuclear Apocalyptic setting (like missile shells and such). If this is the case, then the War definitely caused a Depopulation Bomb.
- Art Evolution: Compare the animation of the third season to the animation of the first. ...Though your take on it could differ depending on which episodes you look at.
- Artifact of Doom: The Ice King's Crown is revealed to be this in "Holly Jolly Secret".
- Marceline's Dad's amulet turns its wearer into a chaotic evil monster dedicated to ruling the Nightosphere with an iron fist.
- As You Know: In "What Have You Done?"
Finn: Our secret mission to capture the Ice King is underway! ...Though I probably shouldn't stay stuff like that out loud.
- Ascend to a Higher Plane of Existence: Ghost Princess in the episode of the same name.
- Ass Shove: Beemo takes advantage of Finn's vulnerable tear-filled state to play Kancho on him. He used his whole hands instead of just his index fingers.
- Astonishingly Appropriate Appearance: Most of the royalty have more human-looking appearances than the other inhabitants of their kingdoms. The most obvious examples are Princess Bubblegum, essentially a pink human woman who lives among much less humanoid candy creatures, and the Ice King, who is the only inhabitant of his kingdom not literally made out of ice or snow other than the penguins.
- Attack Its Weak Point: The Ice King, asking for it:
Ice King: FOOL! Your powers are no match for my magical crown!
- The giant ruby on the Snake-Armed Ruby Brainbeast's back.
- Auto-Tune: Finn sometimes (but not always) sings this way ever since he swallowed a tiny computer sometime in the past.
- Awesome but Impractical: A lot of things.
- Awesome McCoolname: Lord Monochromicorn (Lady Rainicorn's male counterpart).
- Goliad. C'mon, you've gotta admit she's got a pretty awesome name. It sounds like the title of an epic or something.
- Back from the Dead: Princess Bubblegum makes a resurrection potion -- of course, the results are predictable, but at the end of the episode, she completes it and they're back to being alive, not undead.
- As of "Crystals Have Power", Tree Trunks, except she didn't really die.
- In "Mortal Folly" and "Mortal Recoil", Bubblegum was frozen and shattered, then surgically reincarnated as a younger version of herself since the surgeons ran out of pieces to put back together.
- Backstory Horror: It may not seem like this show would have a horrifying Back Story, but when you realize this show takes place After a Nuclear War then the innocence is lost forever.
- The Ice King's origin brings with it a hefty dose of tragedy and creepiness.
- Bad Bad Acting: Finn and Jake do this in "The Duke" to portray to Princess Bubblegum how the Duke of Nuts potentially saved her life. It fails.
- Badass Adorable: Me-mow, who is an assassin that is a tiny cat with a little girl's voice.
- A little girl trying her dead-best to sound threatening. And failing.
- Due to the style of the show many characters can fall under this trope.
- Badass Beard: Billy.
- Badass Cape: Jake turns into one of these and is worn by Finn in "City of Thieves".
- Badass Long Hair: Billy and Sir Slicer. And as revealed in one of the show's best gags, Finn.
- Bald of Awesome: Older Billy.
- Balloon Belly: Finn and Jake get one each in "Business Time". Jake can just compress his belly. Finn can't.
- Batman Gambit: During the episode "In Your Footsteps", a bear starts imitating Finn to the point he tries to take his identity just to be a hero like him. After Finn hurts his feelings, he apologises and gives the bear the Enchiridion so he can be a hero of his own. Turns out this was all a ploy by the Lich to get his hands on the Enchiridion, knowing very well Finn couldn't ignore his selfless nature.
- Beam-O-War: Magic wand vs ice cream.
- Beast of Battle: The Ancient Psychic Tandem War Elephant in "The Limit".
- Beauty, Brains, and Brawn: If we count Flame Princess as a main character, then Marceline, Princess Bubblegum, and Flame Princess, respectively. Marceline has been called "sexy" in-show, Princess Bubblegum is a scientist, and Flame Princess is very hot-blooded and one of the most powerful characters to ever appear on the show.
- The three girls are never used at the same time, so consider the trio they have used of the vampire who's spent the last millennium writing and singing about her feelings, the pink nerd who names her lab-rat "Science" and the little boy who's in his element whenever he gets to swing his sword.
- Beauty Equals Goodness: Seems to be a staple of the show, whether unintentional or intentional, as Finn and Jake are quick to label anyone as "evil" based solely on appearances alone. Marceline, while not exactly Good All Along, is nice to Finn and Jake after they impress her.
- Often Invoked Trope, like in "To Cut a Woman's Hair":
Jake: If she [the Tree Witch] was good, she wouldn't be so ugly...
- Beauty Is Bad: Except when the show makes exceptions, such as with the Guardian Angel and the Dimple Plant.
- Once again played straight with the Fruit Witches in "Dad's Dungeon".
- Flame Princess is a teenager who does seem fairly innocent. However, even her own father calls her evil; and boy, does she show it.
- Beauty Is Never Tarnished: Averted in "Memory of a Memory" when Finn spies on one of Marceline's memories and spots her picking her nose and wiping it on her pants leg.
- "Marceline's Closet" is all about Finn and Jake being trapped in Marceline's closet and watching her do unladylike things while waiting for a chance to escape. This includes nose picking.
- Be Careful What You Wish For: The guardian of the wishes in "The Limit" tries to invoke this on whoever reaches him, but Finn actually was very careful what he wished for and thwarted him. He wished for the ancient psychic tandem war elephant he and Jake wanted, seemingly sacrificing Jake for it. He then had the elephant wish to save Jake and the Hotdog Knights.
- Be Yourself: Arguably the Aesop for "Billy" and "The Real You".
- Beneath the Mask: There are times when Princess Bubblegum shows she's not as innocent (or sane) as she appears, like when she told Finn about the Paralysis Potion she made for no observable reason.
- Likewise, Finn finds out Marceline is a lot nicer than she seems on the surface.
- Beta Couple: Jake and Lady Rainicorn.
- Betty and Veronica: There are light elements of this, with Finn's crush on Princess Bubblegum (Betty) and occasional confused emotions regarding Marceline the Vampire Queen (Veronica) (even though they've made it clear they don't want to date each other).
- As of "Incendium", the formula becomes even more tangled with Flame Princess included.
- Pen himself has admitted that the romantic formula of the show was influenced by Archie Comics featuring Betty and Veronica.
- Beware the Nice Ones: Aside from the fact that both Bubblegum and Finn can get a little... iffy when provoked, apparently the possessor of the most evil soul in Ooo is Gunter.
- But which one?
- Bi the Way: Jake has a secret crush on Billy. Wonder what Lady Rainicorn would say...
- Big Badass Wolf: Not in the pilot itself, but in the opening sequence. Also, Marceline shifts to a werewolf-like form in order to scare Jake early on in "Henchman", implying that she may also be able to utilize this trope at some later point.
- The Party God takes on this form.
- Not to mention the Whywolves and the wolves Marceline runs with in "Go With Me".
- Big Ball of Violence: There's one at the end of "Loyalty to the King".
- Big Beautiful Woman: Rebecca Sugar stated that Susan Strong was created with this concept in mind.
- Big Damn Heroes: Jake really likes to PARRRTY!
- Subverted with Marceline in "Heat Signature":
Finn: You're here now to beat up those ghosts and save us!
- Big "Never!": When Abraham Lincoln tells Finn he needs to believe in himself.
- Also when Finn is asked to slay a Neutral Neutral ant:
Finn: Never... never... NEVERRRRRRR!!!
- And yet again in "Blood under the Skin" when Jake tells Finn to put on the female armor.
Jake: Put on the armor! It'll protect you from evil, even ghosts!
- Big No: In "My Two Favorite People", when Jake sees his girlfriend, Lady Rainicorn, in the arms of his best pal, Finn.
- Finn gets another one when he realizes he's become a thief.
- Jake drops one when Finn threatens to eat all the apple pie in "Tree Trunks"
- Seriously, Jake drops a Big No like every other episode.
- Finn again in "What is Life?" when the Ice King zaps NEPTR the robot with his ice magic.
"Noooooooooooo-- Oh wait, that's what we wanted to happen."
- Another one by Jake in "Guardians of Sunshine" when he thinks Finn is dead.
- And yet another one dropped by Finn in "Mortal Recoil" near the end.
- LSP gets a cool slow-motion one when Finn kicks over her can of beans in "Heat Signature"
- Finn drops the Biggest No yet in "Wizard Battle", reaching Make Me Wanna Shout levels. Jake says that this is the loudest he's ever heard Finn scream. It should be noted that Finn screams a lot.
- The episode preview for "The Apple Thief" made us think we were getting the biggest one yet. Turns out it was fairly normal. Nothing to see here, people.
- Clarence drops one when he kills Warrior Princess.
- Big OMG:
Jake: OH, MY GOB, OH, MY GOB, OH, MY GOB, OH, MY GOB!!!
- Finn drops one in "From Bad to Worse":
Finn: Ohhh, MYYY GLOOOOOB!!!
- Big "What?": Finn lets one drop when Party Pat tells him that he and Jake haven't been partying when Finn thought they were.
- Jake drops one when it is revealed that Flame Princess is evil in "Incendium".
- Big Yes: Finn drops one at the end of "The Enchiridion!"
- Bilingual Bonus: In "My Two Favorite People," this exchange between Lady Rainicorn and Jake after Jake asks her if she knows a joke:
Lady Rainicorn [in Korean]: I can't think of one... but remember the time when we ran naked through that farmer's cabbage patch? (Giggle) He was so offended!
PB: I'm so happy! I could... I could... (attempts to flip bed, then faints.)
- In the end "From Bad To Worse", Lady Rainicorn reveals that she didn't free the zombified Jake due to Idiot Ball.
- The episode title "Morituri te Salutamus" is Latin for "we who are about to die salute you," which is how gladiators would address the Roman Emperor.
- Jake also seems to speak a little Japanese. In the episode where they are trapped in the Nightosphere, Jake encourages Finn with a Japanese line roughly translated as "Do your best very well."
- Bilingual Dialogue: Jake, and apparently no one else, seems to speak Korean as well as Rainicorn. She can understand him when he's speaking English, but he does translate a joke for her once.
- Bittersweet Ending: "Too Young". No, this is not a pun on the fact that Lemongrab is sour.
- Depending on how much you liked Finn and Princess Bubblegum, "Incendium".
- Bizarre Alien Biology: Whenever the Soft People get scared, they cry out their armpits, or "go wee wee".
- Black Bead Eyes
- Black Blood: When Clarence died, he exploded into a pile of spray cheese.
- Blatant Lies: Finn and Jake's promise to stay away from the ghosts' house in "Heat Signature".
- Also this from "It Came From The Nightosphere":
Fluffy Person: Huh? Who the fluff are you?
- From "Still":
Finn: What did you do to us, Ice King?!
- Blessed with Suck: Finn after being transformed into a foot.
- Bling Bling Bang: Finn's golden sword and his twin katana swords. Finn's female counterpart Fionna has a ruby sword.
- The Ancient Psychic Tandem War Elephant has frickin' golden double barrel shotguns for tusks!
- Bloodless Carnage: "Princess Monster Wife" features this.
- Blood Oath: A variation is used in "Slumber Party Slumber", called a Royal Promise. Finn breaking it would have resulted in trial by fire. But since Princess Bubblegum took pity on him, they made his death decided by a math question instead.
- One is mentioned in "What Is Life?", when Finn releases a bunch of balloons from their blood oath after transporting him to the Ice King.
- A Bloody Mess: Finn uses ketchup to resemble bloodshed when the Cuties attack, and they fall for it at first.
- Blue and Orange Morality: Flame Princess seems to mainly think of things in terms of elements before anything else. She also seems to think that everything has a single purpose. She also thinks that hurting her for fulfilling her purpose to burn people to death is unjust. What. Granted, though, she has no sense of normal morality, possibly due to being sheltered.
- Blunt Yes:
Death: Okay... who do you think won?
- Body Horror:
- Finn being transformed into a crystal in "Crystals Have Power".
- Basically all of the Magic Man's spells.
- Borrowed Catchphrase:
- Bottle Episode: "Still". The entire episode takes place inside the tree house and only four characters are featured.
- Bowdlerise: The original title card for "The Enchiridion!" was quite dark. They had a Censor Decoy that was quite grotesque, but the censors didn't fall for it, so the artists who made the picture were told to make it more lighthearted.
- Also, during the imagination zone scene in "What is Life," the storyboards have Ice King teach NEPTR about princess storage. He basically says that if you leave all of your princesses piled on top of each other in a massive pit, they'll keep each other warm and "feed off each other".
- Completely inverted for "Belly of the Beast". In the original, the bears and Finn and Jake get out of the monster safely. In the actual episode, they get scorched in the process of escaping.
- The original storyboard of "Ocean of Fear" has Fear Feaster coming out of Finn's butthole. It was revised to make him come out of Finn's belly button.
- Ice King's line "hit in the boing-loins" was originally "hit in the nuts".
- The original ending to "Fionna and Cake":
Ice King: And then the Ice King married them all! THE END!
You're like a beautiful treasure / I want to open your chest
- After Jake sings "All Warmed Up Inside", the Flame King originally said this:
Flame King: "A fire inside my body"?! That's pornographic.
- A Boy and His Magic Dog
- Bragging Theme Tune: Billy's song in "His Hero".
- Brain Bleach: Jake cowers and shields his eyes while trying to resist the urge to throw up after Magic Man turned a bird inside out.
"Think happy thoughts. Little cute bees. Little babies. Tiny, tiny bunnies."
- The forest animals' reaction to a face on a cow's udder.
Mr. Fox: Yo, put that bag back on!!
- Bread, Eggs, Milk, Squick: Or maybe Squick, Squick, Squick, Super Squick:
Finn: Bleach, gasoline, ammonia, lighter fluid, I dunno, lady stuff. Plutonium...
- Breaking the Fourth Wall: The Easter Egg snail always waves at the viewers.
- The wall finally comes tumbling completely down in "Five Short Graybles" when Cuber hosts the episode and talks directly to the viewer.
"See if you can guess the theme by the end of the episode, okay?"
- Break the Cutie: Happens to Finn twice in "The Enchiridion!".
- Literally played with in "Conquest of Cuteness" when Cute King finds out Finn, Jake, BMO, Lumpy Space Princess, Cinnamon Bun, and a duck faked their deaths using ketchup as blood.
- Brick Joke: "Hey Jake, ever wonder what a demon heart looks like?" End of the episode... "Hey naked kid, how about some free demon heart?"
Jake: Full circle!
- At the beginning of "Evicted!", there was a scene where a worm crawled on Finn's bed. No big deal right? At the end, this happens.
- "Hug Wolf" begins when the titular creature interrupts Finn and Jake destroying an evil tree about to spread its spores. The Hug wolf gets hit by one of the spores when they destroys the tree. Then at the end of the episode, after the curse on both her and Finn is lifted, the spore turns her into an evil tree and attacks everyone.
- Broken Ace: Billy. He gets better, though.
- By the end of Season 3 and beginning of Season 4, Finn was so heartbroken and confused about his emotions that he literally broke down and cried.
- Broken Aesop: Let's just say this show doesn't take the whole And Knowing Is Half the Battle thing too seriously.
- Brown Note: Princess Monster Wife repeatedly inadvertently knocks Fin and Jake unconscious with her appearance, even when they use mirrors to avoid this. She also made a penguin puke, again inadvertently.
- Bunny Ears Lawyer: Princess Bubblegum is eccentric, and a bit Cute and Psycho, but a good Cute Psycho. However, she cares deeply and personally about her citizens and will do anything to protect them. Just don't piss her off.
- When characters call on Finn to be a hero they also deal with the fact that he's a little boy and when they deal with him as a little boy they also must account for his heroic status. This is much less of a factor for the more mature Fionna. (Who actually wears bunny ears.)
- The Bus Came Back: Susan Strong in "Beautopia".
- In "Hot to the Touch", NEPTR of all people came back.
- Butt Monkey: The Ice King
- By the Lights of Their Eyes: Finn and Jake's eyes are visible in the dark in "The Other Tarts".
- Call Back: "Prisoners of Love" has what appear to be references to the pilot: The plot is again to rescue princesses from the Ice King (except this time it's everyone but Princess Bubblegum). They run into the Snow Golem and Iceclops, and the Ice King has a hallucination in which he meets the Cosmic Owl after falling unconscious (and like Finn, he refuses to listen, perhaps because he thought the Cosmic Owl was actually Jake).
Cosmic Owl: "You're a sociopath."
- Later on in another episode "Donny", at the end of the Whywolf's explanation of how the ecosystem works, the Cosmic Owl itself is called back as the top of the food chain and consumes all of the Whywolves in one gulp.
- In "Billy's Song", Billy is seen wearing a large gauntlet with an eye on the back of the hand and a jewel in the forearm. He also has a jewel in place of his nose. In "Mortal Folly" Finn gets the same gauntlet and he and Jake are given headbands with jewels similar to Billy's to protect them from the Lich's powers.
- And then there's this:
Jake: Tree Trunks exploded in the Scary Dark Forest after she ate that crystal gem apple. Remember?
- In the title card for "Memory of a Memory", Mrs. Cow from "Storytelling" can be seen (without her bag). Also, in the episode proper, Finn whispers "Don't eat those [fries]" to the memory of Marceline's father.
- The 3rd season episode "What Was Missing" has Finn and Jake running after the Door Lord for stealing treasured items from everybody. The thing that was stolen from Finn is a lump of Princess Bubblegum's hair that he got from her in "To Cut A Woman's Hair".
- The lump of hair is once again called back in "Incendium".
- In the same episode, the Door Lord looks very similar to the gatekeeper in "The Enchiridion", except with a door on his hat instead of a key.
- "The Creeps" references "Mystery Train", like how Jake fooling Finn into thinking everyone on the train was dead, and using fake skeletons is mentioned, and that Jake's pranked Finn twice now.
Jake: I GOTCHA, dude! TWO FOR TWO!
- "From Bad To Worse" features the zombie virus from "Slumber Party Panic". The difference from the latter is that Princess Bubblegum is unable to create the antidote.
- In "Another Way" Finn is reading in bed while recuperating. The volume in question is the Enchiridion.
- Call Forward: The movie that the characters try to watch at the beginning of "Videomakers" is titled Heat Signature 3. The title of the episode immediately afterward is "Heat Signature". Though it could also be considered a Call Back because "Videomakers" has a higher production code number than "Heat Signature".
- Calling Your Attacks: Finn calls his jump-kick of the Ice King. It's actually a punch. "Psych!"
- In another episode, Finn casts magic enchantments on himself in this fashion. After five of them, completely subverts it by shouting, "AND EVERY OTHER POWER I DIDN'T MENTION BY NAME!"
- Finn "Vampire Kick!" followed by Marceline calling the exact same attack shortly after.
- Canis Latinicus:
- The Donut Witch's spells are a good example of this trope.
Donut Witch: "Go back-icus from whence you came-icus!"
- Actually, magic probably just runs on this in general.
Ash: Ashicus flyicus. (Ash flies away)
- This is inverted with the magic that Finn and Jake's dad practiced and the magic that Flambo possesses.
- Captain Obvious: From "The Eyes":
(Horse drops into Finn and Jake's bedroom)
- From "What Was Missing":
Princess Bubblegum: It's the door of the Door Lord, Finn. We used to lock them up, but they kept breaking out... cuz they're door lords.
- Career Killer: Scorcher.
- To an extent, Me-Mow.
"Me-Mow, Assassin Second-class. But once I take out a princess, I graduate to full membership."
- Caretaker Reversal: In "Storytelling" Jake gets sick and Finn takes care of him, obeying all of his requests, including the one to find a true story to tell him. At the end of the episode, Finn gets sick as well, and Jake rushes to do everything for him as well... until he realises that Finn has just fallen asleep.
- Cargo Envy: Jake has a hard time lampshading this trope. He eventually just explains himself straight-up:
Jake: I bet you wish you were my butt.
- Carnivore Confusion: The Candy Kingdom is populated by candy and other sweets. Lampshaded in "Videomakers", where Princess Bubblegum is shown drinking a sentient smoothie.
- In another episode, Bubblegum is stress-eating a sentient ice cream cone.
- In "Slumber Party Panic", live blindfolded candy people crack candy Zombies open like pinatas and eat their candy guts. Yeah...
- In another episode, Peppermint Butler shows an interest in eating Finn and Jake.
- Rainicorns apparently love the taste of human, but since they are so rare, they eat Soy People. Finn also thinks Soy People are tasty.
- "They say you can hardly tell the difference!"
- Wildberry Princess often makes meat pies, being a fruit and all.
- Cassandra Truth: Finn knows the Secret Guardians of the Library exist in "Paper Pete". The difficulty is convincing Jake they exist.
- "In Your Footsteps" is a subversion. Finn does believe everything Jake tells him about the bear, but it's Jake trying to convince Finn that it is an actual problem that they have trouble with. Finn only realizes it when the bear makes a party in the woods using Finn's identity.
- Catch a Falling Star: In "The Enchridion" Finn rescues a falling Princess Bubblegum by catching her... when she was already only a yard from the ground.
- Subverted in "It Came from the Nightosphere". Marceline sees that Finn and her axe bass are falling from a great height. She rushes over and catches... her bass Just in Time, and lets Finn hit the ground.
- In the final moments of "Incendium", Finn catches an extinguished Flame Princess who is able to relight herself.
- Catch Phrase:
Finn: What time is it?
- Censor Suds: At the Swamp of Embarrassment.
- Cerebus Retcon: The origin of the Ice King's ice powers gets one in "Holly Jolly Secrets."
- Cerebus Rollercoaster: The show has more than 1 of pretty dark Wham! Episode, but outside that, it is still largely funny.
- Cerebus Syndrome: The third season is notably darker and more mature (and less silly) than the previous seasons.
- Character Alignment: The concept of character alignment is referenced In-Universe occasionally, though not in any specifics.
- Except for that Unaligned ant that Finn refused to kill.
- And Hunson Abbadeer's amulet that "fills the user with chaotic evil".
- Check, Please!: "Videomakers" demonstrates that, despite apparently watching tons of movies from our time, none of the characters have learned its proper usage.
- Cartoon Network recently started running an ad for an Adventure Time "mix your own adventure" video creator with two strange, but coherent examples, and then this:
Ice King: I've soiled my tunic!
- Chekhov's Boomerang: The Enchirideon. First is a treasure Finn goes to find, then helps him find an ailment for broken toes in another episode. Now in the hands of the Lich.
- Chekhov's Gun: At the beginning of "The Eyes", Finn and Jake recall the adventures they've had over the past week. One of these involves punching the Ice King, who says "I just want to be happy!" Turns out, he's wearing the horse costume to find out how Finn and Jake are so happy.
- The combo move from "Guardians of Sunshine". Finn fails it at the beginning of the episode trying to beat Sleepy Sam. By the end of the episode, Finn uses the combo move to defeat the now materialized Sleepy Sam.
- During the episode "Fionna and Cake," Fionna's crystal sword, given to her by the Ice Queen as Prince Gumball in disguise, is one of these. Then subverted, when it's revealed to be a trap that encases her hands in ice. Then zig-zagged when she uses the ice to free Prince Gumball.
- Remember Princess Bubblegum's new type of firecracker in "Incendium", those liquid pyrotechnics? They are used to cool off Flame Princess.
- In "Hug Wolf", the Hug Wolf who hugged Finn is hit with a flaming piece of the evil tree Jake destroyed. When Finn and the hug wolf turn back to normal, Jake asks her for a hug. Suddenly her head morphs into the face of the tree.
- Chekhov's Gunman: The snail. Appears in every episode as a minor Easter Egg. Releases the Lich from his prison and becomes his vessel after he is defeated.
- Chess with Death: Well not chess, but Death likes music battles.
- Chest Monster: in "Dungeon", vomiting treasure when awakened.
- The Chew Toy: Cobbler
- Chick Magnet: Finn, oh, so much.
- Ice King gets a taste of this when he turns into the Nice King.
- Jake, to an extent. The imaginary girls from "Rainy Day Daydream" for example.
- A Child Shall Lead Them: Taken Up to Eleven with Embryo Princess, who... yeah.
- Christmas Episode: A two-parter called "Holly Jolly Secrets" is set for the third season.
- Clear Their Name: In "The Duke", Finn has to come to terms with admitting to Princess Bubblegum that the Duke of Nuts did nothing wrong.
- Closed Circle: Happens in "Rainy Day Daydream". A knife storm prevents Finn and Jake from adventuring outside, so they have to stay in the tree fort and imagine their own adventures, which turn out to affect reality.
- Cloudcuckooland: The entire Land of Ooo, but a special mention goes to Lumpy Space, whose denizens are even more bizarre than the rest of the cast.
- Cloudcuckoolander: Everyone. Special mention goes to the people of Lumpy Space (especially Lumpy Space Princess) and Tree Trunks, who attempts to have tea with and seduce monsters (Tentacle monsters) when they attack her. Finn and Jake seem to consider Tree Trunks's idiosyncrasies to be due to senility, however.
- Combining Mecha: In a way; Finn (after being transformed into a foot) combines with several other cursed freaks to create a giant body mech.
- It turns out, after getting uncursed, they just like being combined into a single unit, and just stand on each-others' shoulders to replicate the effect.
- The Cuties do this in battle.
- Comically Missing the Point: Rather subtle if you don't pay attention. In "The Real You", Finn and Jake have to communicate with worms by going into a hollow apple, so Finn and Jake draw faces on their fingers so that they can talk to them. Finn points out that Jake doesn't have to do this because he can use his powers to shrink down, go into the apple and talk to the worms. Upon realizing this, he says "Oh, yeah!" and shrinks down, but he leaves his hand the same size with the face still on it.
- This exchange from "It Came from the Nightosphere":
- And this from "What Have You Done?":
Princess Bubblegum: Please... I beseech your aid, in the name of common decency!
- From "Holly Jolly Secrets" after The Reveal:
Ice King: Now you know my secret... I USED TO WEAR GLASSES!
- This example isn't as comical - it's showing how the Ice King has been under the influence of the crown so long that he doesn't even recognize what's happening on the tapes.
- From "Her Parents":
Jake: So... this isn't human?
- From "Paper Pete":
Finn: (Looks for a way to save Jake from flesh eating mold) Where could I find ways to solve problems in a library? (Notices a sign that says "Books!") Books? (Returns with a large book and starts hitting Jake with it). *screaming* BOOKS, BOOKS BOOKS!
- Continuity Cameo: The businessmen from "Business Time" look a lot like the businessman costume from the Flapjack episode "Kid Nickels", which Pen storyboarded. Also, the adventurer costume looks like Billy if he were a human.
- Continuity Cavalcade: Many characters from past episodes return in "Holly Jolly Secrets".
- Continuity Nod: Has its own page.
- Contract on the Hitman: Ice King tries to use another hitman to get rid of Scorcher.
- Cool and Unusual Punishment: "Poots on newts!" is what Jake gives a giant fire newt for stealing boots. So it's poots on newts for stealing boots.
- Cool Horse: Lady Rainicorn and Lord Monochromicorn.
- Cool Old Lady: Tree Trunks and the old woman who get Finn and Jake to return to beating up evil.
- Cool Plane: Finn's paper airplane skills are something to behold.
Finn: I'll fly the paper as an airplane down the bedroom ladder. It'll triple barrel roll past the kitchen open the fridge and cook some eggs then eat the eggs and unfold itself as it lays itself in front of Marceline's door.
- It does work until the last step, when it lands in a wastebin.
- Cool Sword: Finn's fourth-dimensional sword from "The Real You".
- Finn and Jake's family sword is made out of freaking DEMON'S BLOOD.
- Covers Always Lie: Most of the title cards.
- Cradling Your Kill: Clarence to his victim, Warrior Princess
- Crater Power: There is a HUGE crater in the Land of Ooo's Earth. Presumably, this was caused by the Mushroom War.
- Crazy Enough to Work:
Jake: I went into the mud, and... (unsure) I.. guess I became a magic dog?
- Creating Life: Princess Bubblegum created Lemongrab in her lab.
- The plot of the episode "What is Life?"
- Creator Cameo: Gingerbread man versions of creator Pendleton Ward, storyboard artist Adam Muto, and creative director Pat McHale can be seen in the background in one scene in "The Enchiridion!". Also, Gingerbread Muto can be seen in the Title Sequence (and Gingerbread Rebecca Sugar (Adam Muto's storyboarding partner) for the opening sequence to the Gender Flip episode "Adventure Time with Fionna & Cake").
- Several episodes feature a stubbly, bespectacled face representing character designer Phil Rynda. The face shows up on minor characters and as the symbol used to summon Marceline's dad, among other instances.
- Creepy Child: Marceline as a kid. "I'm hurting you because I love you."
- Cruel and Unusual Death: In "Ghost Princess", Clarence eventually finds out how he died. It was self-induced, yes, but that doesn't make it any less disturbing.
- Crystal Prison
- The Cuckoolander Was Right: In light of the show's post-apocalyptic setting, the Tart Toter's little monologue might not be as crazy as it sounds: on intense over-analysing, it sounds almost like some kind of enviromentalist plea. Maybe.
- Cue the Sun: In "Evicted!" to symbolize that things will start to go right for Finn and Jake. For a while, it doesn't.
- Curb Stomp Battle: Finn vs the Bucket Knight.
Finn: That... suuuuuucked...
- Marceline and Jake vs. Ash.
- Curse Cut Short:
Finn: SON OF A-- (train toots)
- Cute Ghost Girl: Ghost Princess.
- Cute Is Evil: The Cuties from "Conquest of Cuteness".
- Me-Mow may be an assassin, but an adorable one at that.
- The baby pigs from "The Pods". They come out dressed in adorable costumes and seem completely innocent... until they get magic wands and start destroying the town.
- Cute Monster Girl: Marceline. Well, most of the time. Other times, not so much...
- Most of the princesses also qualify for this.
- Cuteness Overload:
Finn: Jake, get the camera!
- Cuteness Proximity: In the episode "Gut Grinder", villagers found Jake to be cute and adorable, showing their affection by heavily petting him.
- Cyclops: The Iceclops. Regular cyclops show up later. Also Earclops.