History HeyArnold / TropesAToI

** Bob and Miriam Pataki, but especially Bob, are abusive to their daughters in different ways. Bob has a horrible temper, is extremely authoritarian, and is [[WhenYouComingHomeDad otherwise obsessed with his work]], while Miriam is always either loopy or [[TheAlcoholic passed out on the couch with]] "[[FrothyMugsOfWater smoothies]]." The two of them pay no mind to Helga, always calling her by her sister Olga's name ([[ParentalFavoritism whom they dote on whenever she's around]]). Meanwhile, their EducationMama tendencies turn Olga into a neurotic mess from having to be perfect for them, to the point that [[TheBGrade getting a B on an otherwise flawless report card]] causes a nervous breakdown, and Olge thinks that [[GrassIsGreener Helga has the better end of the deal]]. "Helga On The Couch" delves into this at length.

* ArtisticLicenseReligion: In "Harold's Bar Mitzvah", Harold's rabbi insists on calling him "Chaim" (much to his annoyance), even though "Harold" is canonically his real name, implying that it's an alternate name used in private religious contexts -- like a Christian baptismal name or confirmation name. But there's absolutely no religious basis for this in UsefulNotes/{{Judaism}}: Jewish children undergoing Bar Mitzvah rites use their birth names.

** Brainy has been given {{Offhand Backhand}}s whenever he tries to be near Helga since the age of three…now nine, [[RunningGag he still does it]].

* DisneyAcidSequence: Helga experiences a bizarre series of hallucinations after drinking an ([[PlaceboEffect alleged]]) anti-love potion in "Helga's Love Potion."

** The first season is a lot different from the other seasons. The animation is of much lower quality, with lots of OffModel scenes, the students are taught by Miss Slovak instead of Mr. Simmons, there were fewer episodes centered on Helga (and she lacked any redeeming qualities for a while, with the abuse and neglect she suffered being used as a form of ComedicSociopathy), Arnold has a crush on Ruth, who is nowhere to be found after season 1, there is a heavier focus on bizarre one-shot characters as opposed to Arnold’s classmates, and on top of all that, Arnold is FAR more child-like and immature compared to the later seasons.

* EveryoneWentToSchoolTogether: In this case, they all went to pre-school together, as revealed in a flashback in "Helga on the Couch." Strangely, even Harold was there, even though a previous episode had made Harold several years older than his classmates.

* EvilLaugh: Curly wins in the best psychotically evil laugh department, but Helga has a pretty impressive one as well. Some of the other characters get one in certain episodes: Sid for example gets on in "Sid's Revenge," and [[BewareTheNiceOnes Phoebe]] gets a brief but creepy evil chuckle in "Phoebe Breaks a Leg."

** Mr. Green is partially based on Creator/ErnestBorgnine's character from ''{{Film/Marty}}''.

** Phoebe takes everything Helga throws at her - however, she gets some CharacterDevelopment, in a few episodes where it's shown Helga ''also'' depends on Phoebe's support.

* EyelashFluttering: In "Dinner for Four," Helga lowers her eyelids at Arnold and bats her eyelids to seem more dainty while taking him, Phoebe, and Gerald out for dinner.

-->'''Phil''': Aw, Pookie. Nobody wants to see ''that''!

-->'''Helga''': Everything that happened today was your fault. You can't do anything right! Take the bus for example. Why do you think we missed it, Harold? Oh, let's see, hmm... maybe was it be because you were too busy eating twice your body weight in chocolate Num-nums?! Oh, how about this one? "Let's take the subway, I think it goes to Lincoln." Oh wait, no it doesn't, it goes straight to the bowels of the underworld!! Population: [[PunctuatedForEmphasis Homicidal! Toothless! Midget clowns!!]] "I know, let's steal their bike, they won't mind." Now, you'd think that would be enough to fill any moron's day, but you're not just any moron, are you, Harold? You're the king! Your day's just getting started! So, because of your amazing curiosity about the world around us, [[TooDumbToLive you pulled the plug out of the bottom of our getaway boat!!!]] You idiot.

* FireAlarmDistraction: The central focus of the episode "False Alarm". Eugene is accused of pulling the school fire alarm and, while everyone else thinks Eugene is guilty, Arnold thinks he was framed. [[spoiler: Arnold's right; it was Curly who pulled the fire alarm]].

*** This spread to other characters who contrast it - in later seasons they were practically total buffoons or borderline immoral jerks, watching some episodes in which the voice of reason is someone like Gerald or even ''Grandma'' seems rather weird.

** Averted in "Buses, Bikes, and Subways" when Mr. Simmons' class sings the "explicit" version of "99 Bottles of Beer on the Wall."

--> '''Sid:''' I bet [Rhonda] thinks I'm a geek because of my big nose!
--> '''Stinky:''' It's not ''that'' big.
--> '''Sid:''' Thanks, but you're only saying that because you have the biggest honker in the world. No offense.
--> '''Stinky:''' None taken.

--> '''Helga:''' I am not taking the subway! ''(cut)'' I can't believe I'm taking the subway!
--> '''Gerald:''' There's no way we're fishing in the swan boat! ''(cut)'' I can't believe we're fishing in the swan boat.
--> '''Arnold:''' We are not calling our go-kart the "[[{{Portmanteau}} Mauve Avenger]]". ''(cut)'' I cannot believe we called our go-kart the "Mauve Avenger".
--> '''Helga:''' Look, I am not going to in there and tell them the truth and end up washing dishes. ''(cut)'' I can't believe I told them the truth and I wound up washing dishes.
--> '''Oskar''': I never lose! ''(cut)'' I can't believe I lost.
--> '''Helga:''' I am not gonna be part of your dumb little football game. ''(gets the shit beaten out of her)'' I can't believe I'm part of their dumb little football game.
--> '''Rhonda''': There is no way I am wearing that shirt! ''(cut)'' I cannot believe I am wearing this shirt.

* GonkyFemme: Patty was at first a girl that was tall and big enough to beat the official bully, Helga, and no characterization was given apart from being scary, strong... and wearing a skirt and a headband. In a later episode she has her own day in the limelight, where she is shown to be [[HiddenDepths feminine, polite and graceful enough to excel in Manner Classes]], even getting to tutor the shows [[GirlyGirl girliest girl]], Rhonda.

** Chocolate Boy's obsession with chocolate is ''very'' similar to a drug addiction. In one episode, he begs Arnold to help him get over this. It is revealed that [[spoiler: his nanny who took care of him as a very young child always gave him chocolate. He was devastated when she was forced to leave him. He ate chocolate to remind him of the one person who ever loved him.]]

** "Weighing Harold": Harold is again given a bet that he can't eat 50 Mr. Fudgie bars in one sitting

** Happens to Phoebe and Helga in "Phoebe Breaks A Leg" - when Helga is indirectly responsible for Phoebe getting injured, out of guilt she starts waiting on her in the way she often had Phoebe wait on her. In a twist, Phoebe quickly realizes this is happening and - tired of being treated like an assistant all the time - [[BewareTheNiceOnes conspires to keep it that way for as long as she can.]]
** Happens to Arnold and Iggy in "Arnold betrays Iggy" - For accidentally blabbing an embarrassing secret of his friend Iggy, Arnold unsuccessfully tries to apologize to him. When Iggy finds out the truth, he begs Arnold for his forgiveness.

** In "Gerald's Tonsils" Gerald tries to practice singing with with his new post-tonsillectomy voice and a kid overhears him and makes fun of it, saying he has a "crazy voice." The kid has a very annoying and nasally voice himself.
** In "Helga's Masquerade" Harold makes fun of Helgs's BigOlUnibrow despite the fact that Harold has a unibrow too.

--> '''Pookie''': Just remember, Arnold. Violence is not the answer.
--> ''She karate chops a watermelon to slice it, hard enough to splatter some of it across the wall.''

-->'''Harold''': If I had a dime for every time somebody called me dumb...[[IResembleThatRemark I'd sure have a whole bunch of dimes!]]

** Arnold learns it in "Mugged." He ends up becoming an ArrogantKungFuGuy who ended up inadvertently chopping the clothes off of some guy who was looking for the bus stop.
** In the episode "Career Day," Helga comments that the ''jujutsu'' class she took really helped her when taking down the perps she encountered on her police "ride-along."
* ImOkay: the catchphrase of Eugune said when something bad happens to him.

* InstantTasteAddiction: In the episode "Chocolate Boy," Arnold tries to help Chocolate Boy overcome his [[TrademarkFavoriteFood already-established addiction to chocolate]] by introducing him to other foods such as carrots, celery, peppers, and radishes; the radishes somehow reminds Chocolate Boy of his favorite treat and soon begins binge snacking on them instead of chocolate - something Arnold decides he needs to be broken of in the end.

-->'''Lt. Major Goose''': [[LampshadeHanging YOUR HAIR'S NOT CURLY!]] WHAT'S YOUR REAL NAME?
-->'''Curly''': Thaddeus.
-->'''Lt. Major Goose''': *{{beat}}* CURLY, GO STAND OVER THERE!

* IWasBeatenByAGirl: Harold by Big Patty in an arm wrestling match in "Harold vs. Patty". He is so upset, he attempts to escape from those mocking him by hiding under a drinking fountain. He finally gets over it by the end of the episode - after she beats him again in the citywide arm-wrestling championships - and smacks Sid and Stinky together when they [[TrashTalk trash talk about him]] after his loss, but not before publicly defending Patty as the better opponent. (The end of the episode implies a RelationshipUpgrade for Harold and Patty due to this.)

** Harold often grumbles "Madame Fortress Mommy'." Whenever he's scared he usually cries out [[IWantMyMommy Mommy]]!

*** In the April Fool's episode Arnold borrows it and turns it around:

** Harold has a tendency to say, "I was hungry!" whenever people look at him for eating something he shouldn't.

** In fact, Arnold is probably the character that got the ''least'', and what little he ''does'' get usually pertains to his feelings for his LoveInterests. After pining after Ruth [=McDougal=] for most of the first season, he finally goes on a date with her in "Arnold's Valentine" and almost instantly loses interest after spending time with her. His more notorious attraction to Lila, which began in season 3 with "Arnold & Lila", actually comes to an end in "Timberly Loves Arnold", late in season 5. Tellingly, in "Eugene, Eugene!", which immediately followed "Timberly Loves Arnold", he shows absolutely no interest in her - even in a scene when he and Stinky are watching her audition (while Stinky fawns over her). Lila also has no more speaking parts after this and it's been confirmed that she will not appear in ''The Jungle Movie.'' [[spoiler: This since has become a case of either LyingCreator or ChangedMyMindKid, as she can be seen in the SDCC clip, but [[DemotedToExtra didn't do anything important]]]]

** Harold began as genuinely mean spirited and brutish. By the later episodes he is so pitiful and sensitive his aloof mask of jerkassery is near completely transparent.

* ChuckCunninghamSyndrome:Suzie and Principal Wartz doesn't appear in Hey Arnold The Jungle Movie.

* CloudCuckooLander:

--> "Hey! Crazy lady! Come back here with my bulldozer!!"

** Principal Wartz, too. During the flood, he dressed in Mexican garb and danced around, then climbed onto the school roof and started singing. He later quit his job as principal for an episode to seek a career as a singer.

* ConsolationWorldRecord: [[spoiler: "World Records" has everyone in Hillwood try and fail to break a lot of world records, but end up breaking the record for the most record-breaking attempts to ever be attempted!]]

** Lila mentions she gets sick on the big amusement rides in "Love and Cheese". After riding the coaster in "Timberly Loves Arnold" she's seen throwing up
** The premise of "Beaned" calls back to the plot of "Dangerous Lumber," showing that Arnold still has a perfect record for beaning people with baseballs. And the plot of "Dangerous Lumber" could be seen as continuing off of the event that kicked off "24 Hours To Live."
** In the episode where Arnold tries to help Chocolate Boy overcome his chocolate addiction Gerald mentions several of Arnold's past accomplishments which were all from past episodes.
--> "Helped Stoop Kid and The Pigeon Man, found Mr. Hyunh's daughter, saved Mighty Pete, stopped the teachers strike..."

--->Arnold: Here lies Cynthia Snell. She lived her life and went straight to... I can't read the rest.

--> '''Grandpa''': We're going to Davy Jones' Locker!
--> '''Jimmy''': Kicking the bucket!
--> '''Grandpa''': Buying the water farm!
--> '''Jimmy''': Checking out of the Hotel of Life!
--> '''Grandpa''': And checking into the Hotel of Death!
--> '''Jimmy''': The Big Roundup!
--> '''Grandpa''': The Last Tango in Paris!
--> '''Jimmy''': The Last Tango in Paris? [[LampshadeHanging That's not a euphemism for dying!]]
--> '''Grandpa''': I know but it was my turn and I ran out of euphemisms and I didn't want to lose the game!

* DeceasedParentsAreTheBest: Arnold's parents, Miles and Stella, were assumed to be deceased during the original run, and therefore fell into this trope. They have devoted their lives to working with and healing the inhabitants of remote jungles. In the ultimate saintly move [[spoiler: they left Arnold with his grandparents after being pressured to go on one last mission--and never came home.]] In ''The Jungle Movie'' it is revealed that [[spoiler:they fell to the sleeping sickness they were working on curing, and were comatose for nine years. They recovered along with the Green Eyes tribe when Arnold and Helga activated the machine that spread the antidote throughout the Green Eyes' encampment.]]

** Ironically, this receives the same treatment in "Deconstructing Arnold". Helga starts the episode by calling out on Arnold that he is too much of a NiceGuy that ruins fun for everyone but the problem is that Helga's only good at this because she is a JerkAss and merely uses this method to bully him. What results is a short life without Arnold who '''IS''' the only one who kept everything in order and that includes the school. Once he stops helping his friends, they began to suffer from their foolishness. The kids then turn to Helga for help but she lacked the wisdom and any sort of social skills (minus Phoebe) Arnold has causing the problems to grew even worse such as Curly humiliating Rhonda, Sid losing his friendship with Lorenzo and Harold and Stinky injuring Eugene. She even lampshades how much of a terrible person she is. Who are the kids going to hate more? Arnold or the UnwittingInstigatorOfDoom.

* DependingOnTheWriter: A lot about the way the kids relate to one another change depending on the plot - which makes a bit of sense for grade school kids.

** Helga's relationship with Arnold - sometimes Arnold sees her as a bullying nuisance and doesn't seem to like her very much ("Girl Trouble"; "Summer Love"; "Married"; and ''particularly'' "Egg Story", so much that it seems out-of-character), whereas other times, it's evident that he is aware that her abrasive attitude is a cover of some kind and approaches her as a friend regardless of her behavior ("Helga vs Big Patty"; "School Play"; any episode where Helga has a family problem and Arnold gives her advice).

--> '''Arnold''': Grandpa, you did not fight Adolf Hitler! You're making this all up.
--> '''Grandpa''': Okay, ya got me. I made that part up. It was Goebbels.

* AbsurdlySpaciousSewer: In ''Sewer King", Arnold and Gerald encounter the Sewer King in the sewers, which are way more spacious than real life sewer systems.

-->'''Arnold''': ''(to Chocolate Boy)'' Go to the fire station, tell them we're stuck in a tree, and we need help getting down.\\
'''Eugene''': Tell them Eugene sent you. They know me. They rescued me many times before.

** In "Helga's Masquerade" Helga learns that she does not need to act exactly like Lila to be liked by Arnold, but generally acting nicer will earn her his love. In her next appearances, she's back to jeering at Arnold.

** Olga always addresses Helga as "Baby Sister," and when she hangs out with Lila in one episode (as part of the "Big Sis, Little Sis" charity) addresses her as "Little Sis."

* AllJustADream: [[spoiler: "Arnold Visits Arnie" ends with the revelation that Arnold only dreamed about visiting his cousin Arnie.]]

** Eugene. He has a room decorated with rainbows and unicorns, and often takes interest in anything related to dancing and musicals.

** In "Harold the Butcher," when Harold has to see his rabbi because he stole a ham from Mr. Greene's butcher shop, the rabbi tells Harold that stealing violates one of the Ten Commandments. However, he goes on to say "most importantly, you stole a ham," referring to Jewish dietary laws. Apparently, if Harold would have stolen some lamb or some other food permitted by the Torah, Harold's sin wouldn't have been as bad.

* ArtisticLicenseBiology: In "Roughin' It" Phil claims moss always grows on the north side of trees, which is a common misconception. In reality, moss doesn't care what side of the tree it's on; it grows where the tree is the most moist.
* ArtisticLicenseReligion: In "Harold's Bar Mitzvah", Harold's rabbi insists on calling him "Chaim" (much to his annoyance), even though "Harold" is canonically his real name, implying that it's an alternate name used in private religious contexts--like a Christian baptismal name or confirmation name. But there's absolutely no religious basis for this in UsefulNotes/{{Judaism}}: Jewish children undergoing Bar Mitzvah rites use their birth names.
* AsideGlance: Arnold looks toward the viewer at the end of "Arnold Saves Sid" [[spoiler:He looks directly at the screen though.]]

* BeatWithoutABut: A variant in "Dino Checks Out." The funeral of the (seemingly) late Dino Spumoni has a "eulogy" from one of his music partners:

* BewareTheQuietOnes: Discussed at the end of "Curly Snaps."
-->'''Mr. Simmons:''' I think we all learned a valuable lesson here today.
-->'''Helga:''' Yep. Don't ever trust the quiet ones. They'll go bonkers and hole up in the principal's office.

** Seymour, as revealed in "Eating Contest", is able to eat an assload of ice cream in one sitting despite his small size. However, [[spoiler: Arnold beats him]].

** As seen in "Phoebe Cheats" Phoebe's house has several rooms that look like they should be in a mansion, like a sparring room and a jacuzzi room.

--> '''Helga''': Qualm. Q-u-a-'''l'''-...''(looks at her father)''...-x?
--> '''Bob''': WHAT?!
* BigLippedAlligatorMoment: An in-universe example in "The Flood," when Helga catches Principal Wartz attempting to dance the salsa while she was trying to break out of the school. The characters-in-question even agreed that [[LetUsNeverSpeakOfThisAgain they'd never speak of it again.]]
--> '''Principle Wartz''': This moment never happened.
--> '''Helga''': Gotcha.

** In another episode the kids get stuck on the subway with a few other adults in the same car, one of which is a blind man wearing sunglasses that harasses Harold in particular for being fat.

** In "Eugene Goes Bad", Eugene finds that his idol "The Abdicator", an [[NoCelebritiesWereHarmed Arnold Schwarzenegger-esque]] ActionHero is not a real ActionHero, but a fictional character played by a JerkAss that's [[NiceCharacterMeanActor obnoxiously spoiled, bosses the staff on the set around]], and [[StuntDouble doesn't do his own stunts]]. Upon finding this out, Eugene does a temporary FaceHeelTurn that ends when the actor saves him from falling to his death, showing that, for all his flaws, he's a fundamentally good person who cares about his fans.

-->'''Helga''': She's nothing but a stuck-up, sixth grade-y, training bra-wearing, brace-y faced, [[DepartmentOfRedundancyDepartment sixth grade-y...sixth grader!]]

* ButForMeItWasTuesday: A heartwarming example--in the Veterans' Day special, it turns out that Gerald's father is a Vietnam War veteran. However, he was sick with the flu during most of basic training, so he was unable to partake in any actual combat and mostly worked as an office clerk--in fact, the only real action he saw was when he once happened to come upon a fallen soldier who had a severe leg wound. Gerald's dad explains that he used some spare files to create a makeshift bandage for his leg--Mr. Johansen didn't think anything of it (he was just helping someone who happened to really need it). Twenty years, while Gerald and his dad, with Arnold and his Grandpa Phil in tow, are in Washington DC at the Vietnam War memorial for soldiers, they run into the same man that Gerald's dad had saved in Vietnam--the man reveals himself to be named Private Miller and explains to Gerald's dad that if he hadn't done what he did to help in the war, he would've bled to death. Private Miller (who's with his wife and kids) adds that he's been waiting twenty years to personally thank him for ultimately saving his life.
* ButNotTooForeign: Phoebe has a Japanese dad and a white mom. Plus, Phoebe's last name, Heyerdahl, certainly isn't Japanese - unless her dad is only of partial Japanese descent.

** Sid, Stinky and Harold to a lesser extent than the former and latter.

** [[spoiler: In "Married", Rhonda repeatedly tells Arnold that he will marry Helga (via a marriage predictor). The only one who believes it is Helga, but as per the word of Craig Bartlett, they do get married in the future.]]

--> '''Arnold:''' I think you're thinking what I'm thinking.
--> '''Gerald:''' ''(whispers in Arnold's ear)''
--> '''Arnold:''' That's even better than what I was thinking.

--> '''Arnold:''' You're a bold kid, Gerald.
--> '''Gerald:''' [[HeyThatsMyLine Hey, that's my line.]]

* HeroesWantRedheads: Arnold is attracted to the red-headed Lila.

* HealthyGreenHarmfulShield: When camping, Grandpa reminds Arnold that red, not green berries are safe to eat using the mnemonic rhyme as seen in the page quote. Arnold always thought the rhyme said "green and sweet," with predictable results.

** Ironically, this receives the same treatment in "Deconstructing Arnold". Helga starts the episode by calling out on Arnold that he is too much of a NiceGuy that ruins fun for everyone but the problem is that Helga's only good at this because she is a JerkAss and merely uses this method to bully him. What results is a short life without Arnold who '''IS''' the only one who kept everything in order and that includes the school. Once he stops helping his friends, they began to suffer from their foolishness. The kids then turn to Helga for help but she lacked the wisdom and any sort of social skills(minus Phoebe) Arnold has causing the problems to grew even worse such as Curly humiliating Rhonda, Sid losing his friendship with Lorenzo and Harold and Stinky injuring Eugene. She even lampshades how much of a terrible person she is. Who are the kids going to hate more? Arnold or the UnwittingInstigatorOfDoom.

* DeadArtistsAreBetter: In an in-universe example, one episode involves Dino Spumoni faking his death to rekindle an interest in his music and raise his sales.[[spoiler: It works too well as a Dino-impersonator comes along, doing his songs and gigs, dates his former wife, and his dog loves him, and drives Dino jealous and reveals he isn't dead.]]

** In "Girl Trouble", Arnold is fed up with Helga's bullying and goes to his Grandpa for advice. Phil guesses that the reasons she bullies him is because she likes him, pointing out that a girl named Gertie (who turns out is Arnold's Grandmother) did the same thing to him when he was younger. Arnold dismisses this theory.

** Bob and Miriam Pataki, but especially Bob, are abusive to their daughters in different ways. Bob has a horrible temper, is extremely authoritarian, and is [[WhenYouComingHomeDad otherwise obsessed with his work]], while Miriam is always either loopy or [[TheAlcoholic passed out on the couch with]] "[[FrothyMugsOfWater smoothies]]." The two of them pay no mind to Helga, always calling her by her sister Olga's name ([[ParentalFavoritism whom they dote on whenever she's around]]). Meanwhile, their EducationMama tendencies turn Olga into a neurotic mess from having to be perfect for them, to the point that [[TheBGrade getting a B on an otherwise flawless report card]] causes a nervous breakdown. "Helga On The Couch" delves into this at length.

** The original pilot episode of the series depicted most of the characters as having differently-colored clothes and gave Gerald a more saturated skin tone.

* ExposedEmbarrassingPurchase: "Helga's Makeover", when Helga wants to show that she's feminine to attend Rhonda's slumber party, she goes to a corner store to buy a preteen beauty magazine for makeover tips, [[CoverUpPurchase along with other magazines to cover it up]]. Unfortunately, the cashier has trouble scanning the beauty magazine and shouts to her co-worker asking for the price for it while describing the magazine, which gets the attention of all shoppers. Helga quickly pays for all the magazines and then runs out of the store embarrassed. It certainly didn't help that the cashier explicitly described the magazine as "the one that gives ugly girls tips on how to be pretty."

* CoolLoser: In "Cool Party" Gerald is on the "geek" list. Subverted in that Gerald was only put on the "geek" list by Rhonda because [[DisproportionateRetribution he beat her for the position of Class President in 2nd grade]].

* AerithAndBob: Among the students at P.S. 118, there are kids who have regular names (Arnold, Gerald, Helga, Rhonda, Eugene, Harold, Phoebe etc.) and those with strange, uncommon names (Stinky, Brainy, Curly, Chocolate Boy, Peapod Kid etc.).

* DetentionEpisode: "Full Moon", Harold, Stinky, and Sid {{moon|ing}} Principal Wartz. Arnold is the only witness, and he refuses to rat them out because he's "[[HonoraBeforeReason not a rat]]", so Principal Wartz gives Arnold 30 days of hard labor in detention. If Arnold confesses before the end of the deadline, Principal Wartz will lift his punishment, and if he doesn't, he will mark Arnold as a "Failure to cooperate" on his permanent record, but Arnold still refuses to rat his friends out. Near the end of the episode, Harold, Stinky and Sid's guilty consciences catch up with them and they confess what they did to Principal Wartz just before he can mark Arnold as a failure to cooperate.

* DetentionEpisode: "Full Moon", Harold, Stinky, and Sid {{moon|ing}} Principal Wartz. Arnold is the only witness, and because he's not a snitch, he refuses to rat them out, so Principal Wartz gives Arnold 30 days of hard labor in detention. If Arnold confesses before the end of the deadline, Principal Wartz will lift his punishment, and if he doesn't, he will mark Arnold as a "Failure to cooperate" on his permanent record, but Arnold still refuses to rat his friends out. Near the end of the episode, Harold, Stinky and Sid's guilty consciences catch up with them and they confess what they did to Principal Wartz just before he can mark Arnold as a failure to cooperate.

* BiggerOnTheInside: As seen in "Phoebe Cheats" Phoebe's house has several rooms that look like they should be in a mansion, like a sparring room and a jacuzzi room.

** While Arnold is the kid with his name on the show's title, the series doesn't focus only on him. There's a certain (and rather large) group of characters that appear pretty darn often: [[{{Deuteragonist}} Helga]], Harold, Gerald, Phoebe, Sid, Rhonda, Stinky, Eugene, Mr. Simmons, Big Bob, Miriam, Grandpa, Grandma, Oskar, Ernie, and Mr. Hyunh.
** Then there's characters that appear fairly often, but not quite enough to be considered part of the main circle: Principal Wartz, Curly, Lila, Brainy, Suzie, and Olga

* ChuckCunninghamSyndrome:
** Mr. Hyunh's daughter Mai was never seen again. Possibly justified - after all, she presumably had adoptive parents in the US, given that her father hadn't been in her life for about 2 decades. She is mentioned only once, in "Family Man".
** Ruth [=McDougal=] (the sixth grader Arnold had a crush on in the first season) mysteriously disappears towards the middle of the series. One could guess that she simply graduated from P.S. 118, since she was already in sixth grade, and Arnold never mentions her (or his crush on her) after the Valentine's Day episode in which Arnold tries to go on a date with both Ruth (who thinks she's seeing a famous poet named "Anonymous") and his French pen pal, Cecilia, and discovers that Ruth isn't all that bright or interesting to be around. In "What's Opera, Arnold?," she appears mainly for Helga to have a foil in Arnold's dream opera. Afterwards, she only cameos two or three times.
** Tucker, Coach Wittenburg's son. Appeared in one episode and was never seen or mentioned again. Odd, since Coach Wittenburg gets a few focus episodes. It's particularly glaring when one such episode deals with Wittenburg's estrangement from his wife. [[spoiler: He finally reappears in ''The Jungle Movie'' alongside his parents.]]
** Mr. Smith (the first season boarder whose face nobody sees) never appears after "Door #16"
** Lana Vail, the brunette woman who lived in the boarding house, also disappears midway through the first season, but shows up in background shots on occasion; for example, at the restaurant with the cockroaches in "Dinner for Four". Some sources say that her original characterization was considered too inappropriate for Nickelodeon[[note]]She would frequently flirt with Arnold, who is nine-years-old and would be creeped out by it.[[/note]] so they dropped her altogether.
** Mr. Purdy also disappeared after only a quick gag in one episode. The boarding house sure suffered a loss of business after season 1.
** Torvald seems to have completely disappeared after only a few appearances.
** Billy, a member of the geek ensemble introduced in "Eugene's Bike" disappeared without a trace after the first season.
** Inverted with Grandpa's sister Mitzi, who appeared out of the blue with no previous mention during the fourth season. However, she also never made any other appearances afterwards.
** Ludwig never appeared again after his debut episode despite the implication that he and Wolfgang would join forces from then on.