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* BaseBreaker: Fred Fredburger became this after being extremely overused in CN's promos along with the excessive overuse of his [[TrademarkFavoriteFood nachos]] and [[ToiletHumor poopoo jokes]].
** As was Mandy, after she became a JerkSue in later seasons.
** Billy, between fans who find him hilarious and fans who find him annoying and one-note.
* BrokenBase: Over whether the show becoming increasingly DenserAndWackier was a good or bad thing.
* CrackPairing: Dean Toadblatt and a giant squid, canonically.
* CrossesTheLineTwice: The Christmas special. Features such things as a mall being burned to the ground as the MallSanta is mercilessly beaten (with The Grim Reaper implying that this happens all the time and Billy blaming it on the sad state of the economy), [[BadSanta evil vampire Santa]], Santa's evil vampire wife, and [[CrowningMomentOfFunny the school bully being eaten by a pack of flying vampire elves.]] An average ChristmasEpisode of a show is packed with heartwarming moments and the old theme about "family and friends being the true meaning of the holiday season," but this show proves that you can have none of that and still be entertaining. Combine that with the fact that this is a ''children's show'' (by Creator/CartoonNetwork's more-or-less loose standards) and you get a truly dark (and hilarious) episode.
** A lot of the humor can dip into this, it being BlackComedy.
* DarknessInducedAudienceApathy: With how grim and crapsack the world is and how unlikable Billy and Mandy can be to some, this can happen.
* DudeNotFunny: Some of Grim's misfortunes and suffering can fall under this.
* EarWorm: [[VillainSong BRAINS, BRAINS, I WON'T LIE. I'LL EAT THEIR BRAINS UNTIL THEY ZOMBIFY!]]
** The first end credits theme. "''Grim and Eeeeeeevil. Grim and Eeeeeeeevil.''"
* EnsembleDarkhorse: [[TheDitz Fred Fredburger]], [[VerbalTic yes!]]
** Jack O'Lantern has also gained himself a sizeable fanbase, [[OneSceneWonder despite only having appeared in a Halloween Special.]] [[PopularityPower This is possibly the reason he was included in the video game.]]
** Dracula.
** Skarr, the only mainstay from "Evil Con Carne".
** Admiral Wolverine Lightningbolt.
** [[GreekChorus Sir]] [[MetaGuy Raven]].
** [[{{Music/Voltaire}} The evil brain-eating meteor]].
** [[EvilIsSexy Eris]], the goddess of chaos.
** Hoss Delgado. He was popular enough that he ''nearly'' starred in the spinoff-series-turned-TV-Movie, ''Underfist''.
* EvilIsSexy: Eris. Never mind the gap in her teeth.
* FamilyUnfriendlyAesop[=/=]SpoofAesop: Billy learns from his inner frat boy that, just because someone is different from you, you shouldn't be afraid of them. You should be '''angry''' at them!
* FountainOfMemes: Probably one of the most quotable Cartoon Network shows ever, especially in the earlier seasons.
* GeniusBonus: The episode where Billy meets mushroom-growing dwarfs has a scene where he escapes from Yogi and Boo-boo by hiding in a cave. Brown bears really are afraid of caves.
** The show is filled to the brim with horror movie references, most of which are fairly obscure even to adult fans.
* GrowingTheBeard: Generally agreed to be around the time this show split off from ''Grim & Evil''.
* HilariousInHindsight: In one episode, Grim is seen watching a Franchise/MyLittlePony parody called "My Troubled Pony" and enjoying it very much, in spite of the fact that he's a male adult and he's clearly not within the show's demographic. [[WesternAnimation/MyLittlePonyFriendshipIsMagic Fast forward to 2010...]]
** Nergal is a [[NoodlePeople tall and thin]] HumanoidAbomination with CombatTentacles and wearing a [[BadassInANiceSuit suit]]. Now [[Franchise/TheSlenderManMythos who does that sound like]]?
** In the beginning of ''Big Boogey Adventure'', Billy doodles "cops fighting dinosaurs" instead of writing out plans, and then remarks that "they should be working together" when Irwin calls him out. [[Webcomic/AxeCop It wouldn't be the last time that concept came up.]]
* JerkSue: Mandy, DependingOnTheWriter.
* MemeticBadass: Hoss Delgado.
* MemeticMutation: See OverlyLongGag on the main page.
** [[{{Music/Voltaire}} Well hello little boy! Don't be shy! Step right up, I'm a reasonable guy! Don't be frightened by the look in my eye, I'm just your average evil meteor from outta the sky!]]
** Judge? Where are the nachos?
*** Yes!
*** I can spell my name real good! F-R-E-D! F-R-E-D! B-U-R... G! E-R! [[TheDitz Fred Fredburger]], yes!
** YOU DON'T TELL DRACULA WHAT TO DO! DRACULA WAS BORN KNOWIN' WHAT TO DO!
*** Vampires don't suck! They scrape! And lick! Scrape! And lick!
** Do not cry for him. DO NOT CRY!
*** YOU FOOLS! YOU'VE MESSED WITH THE NATURAL ORDERRRRRRRRRR!
*** IMPORTANT! COMMERCIAL! MESSAAAAAAAGE!
** Grim was the original brony.
** Grim's Peanut Song from Episode 2: "Look at me, I'm a kitty cat! I wear a bowl of peanuts for a hat. If I eat them all, I will get fat! Blah blah blah I'm a kitty cat!"
** LIKE AN ANGRY WOMAN.
** Lord Byron is Billy's [[JoJosBizarreAdventure Stand]]!
* MoralEventHorizon: Quite a few, though they're offset only by the show's NegativeContinuity (usually).
** Grim and Mandy have had a number of potential moments, usually involving leaving Billy to a CoolAndUnusualPunishment.
** Billy, though a good kid, has tried to kill his "adopted" son just because he's afraid of spiders.
** Irwin has allowed a Pyramid to be built in his honor, regardless of whether or not everybody remains brainwashed.
** Nergal forces a number of people into transforming into his "[[WasOnceAMan Friends]]" in the second episode he appears in.
** Boogie crossed it in ''Wrath of the Spider Queen.'' During the contest for who would become the future Grim Reaper, Velma was close to winning, but Boogie decided to rig the voting. When Velma finds out, [[spoiler: she thinks Grim tried to cheat]], costing him his only friend.
* MostAnnoyingSound: DESTROY US ALLLLLLL!!! DESTROY US ALLLLLL!!!
** To a lesser extent, any time Billy laughs.
* NauseaFuel: Several times in the show.
** Many of the injuries, such as when Pud'n [[EyeScream gets an eye full of cactus and pulls it off, revealing a hideous, skinless red eye]].
** Or Billy's nose popping.
** Or when the closing iris closes on Billy's head and a bunch of blood and snot sprays from his nose and his eye pops out.
** Or when Billy and Mandy force Grim to resurrect the school mascot cats. That, in itself, is pretty bad, but when Billy asks one of the cats to scratch his back...his skin and muscle get shredded by the splintered claws of the undead cat, and his spinal column pokes out.
** In the episode, "Zip Your Fly," Mandy accidentally swapped her head with that of a fly after messing with Grim's zipper. That's pretty standard for the show, but then after losing the zipper to the dump, she ends up eating ''the entire landfill'' before she can find it and get her body back.
* TheProblemWithLicensedGames: Averted. The video game based on the series is a surprisingly fun beat-em-up style fighter with plenty of characters from the show, all voiced by their actual voice actors, with Music/WeirdAlYankovic as the announcer!
* TheScrappy: Billy is this to more than a few viewers, due to how arguably flat he is as a character and for being a often pointless ToiletHumor dispenser. He's even this in universe.
** Fred Fredburger is also this in universe, ''[[EveryoneHasStandards even managing to annoy]]'' '''Billy''' ''with his stupidity''. Among viewers, though, he's a BaseBreaker, with many who love him and many who feel he ended up over-used. (Although he wasn't half as over-used as characters like [[WesternAnimation/FostersHomeForImaginaryFriends Cheese and Goo]].)
** Mindy is one of the most annoying {{Alpha Bitch}}es ever created.
* SeasonalRot: The final season is considered pretty crappy, though Underfist is well-regarded.
* TearJerker: In "Son of Nergal", Junior attempts to fix his teddy bear, Mr. Bonkers, after Mandy rips its head off.
-->'''Junior''': It's *sniff* going to be okay. I'll put you back together and *sniff* you'll be my friend and I'll be your best friend...
** Billy saying goodbye to his pet chupacabra Daisy.
** The flashback in ''Wrath of the Spider Queen.''
* ToyShip: Admit it- you've all considered this for Billy and Mandy at least ''once''.
** Or Irwin and Mandy.
** [[HoYay Or Billy and Irwin]].
** Or Junior and Mandy, to a lesser extent than the other two.
* UnfortunateImplications: Billy, according to the ChristmasEpisode, is [[InformedJudaism Jewish]]. He's the character with the large, bulbous nose. This may be why it's never brought up again. [[note]]Though the standard Jewish stereotype is a large, ''hooked'' nose. Close enough.[[/note]]
** Sperg is a bully with implied mental health issues. The word "sperg" is also used as an ableist slur towards people with UsefulNotes/AspergersSyndrome, who are commonly accused of faking their disorder as an excuse to bully people.
* WhatDoYouMeanItsForKids: Like nearly all of Creator/CartoonNetwork's in-house programming (specifically those from the "Cartoon-Cartoon" era of shows), this show is a kids' cartoon on the outside, and on the inside, is packed with a lot of things that most normal channels wouldn't allow to touch children's animated shows. In the case of this show, it's BlackComedy, some mild sex and toilet humor, and disturbing imagery that makes ''WesternAnimation/InvaderZim'' look like ''My Little Pony''.
* WhatTheHellCastingAgency?: GilbertGottfried as ''SantaClaus''.
* TheWoobie: Pud'n and Jeff. Also, Skarr. He is just trying to move into the neighborhood, trying to avoid his previous life as TheDragon[=/=]TheStarscream.
** Billy, at times.
** JerkassWoobie: Grim has his moments too.

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