* AlasPoorScrappy: Wether you love or hate the duo, the former's treatment in the second half of "Precious Pig" where he is shunned and banished to the back of the classroom after he is accused of hurting Precious; given he attempted and succeeded to teach him karate.
* AlternateCharacterInterpretation: Sigmund's nervous "Oh? Friends? Ahaha! Such happy for you!" was a brief unmasking of his haughty facade. Perhaps ''he'' was jealous of Kyle for having friends, which he--possibly--does not have (it would make sense, considering how arrogant he is) and decided to invite himself to the dinner at Kyle's house so he could humiliate Kyle (which he achieved, since Kyle admitted he was worse than him in the end) to make himself feel better? The [[AnAesop aesop]] of the episode seems to support that theory--after Sigmund left, Kyle was in a defeated state, until Fanboy and Chum Chum assured him that he still has his friends, to which the reply was "Yes... I suppose I ''am'' the winner after all".
* AssPull: [[spoiler:The Dollarnator]] at the end of "Dollar Day".
* BaseBreaker:
** The titular characters have their fans, however they're also the main reasons why some people can't stand this show.
** Yo is either cute or annoying, depending on whom you may ask.
* [[BigLippedAlligatorMoment Big Lipped Alligator Series]]
* CriticalDissonance: Some people and reviews have given the show ''extreme'' backlash. That being said, the show won five Emmys (the most any Nicktoon has been awarded tied only with ''ElTigre''), and it's premiere episode gained almost six million viewers.
* EarWorm: "Here we go, 'cause we're Fanboy Chum Chum! [[{{Understatement}} A little cuckoo]] Fanboy Chum Chum!".
* EnsembleDarkhorse: Kyle. A self-aware SnarkKnight magician with a backstory similar to that of Harry Potter? Yes, please.
** Sigmund gathered a large fanbase long before he even made an appearance in the show.
* GermansLoveDavidHasselhoff: The show is/was actually pretty popular in Latin-American countries, selling much more merchandise than in its own.
* HilariousInHindsight: A Frederator-made Nicktoon that features a tall youth and a shorter one with dark hair who tend to annoy an outsider with unusual powers trying to fit in with normal kids and one of them is british; [[WesternAnimation/MyLifeAsATeenageRobot sound familiar?]]
** Heck, Kyle even kinda looks like a Rule 63 version of !Human Jenny with the red hair and freckles.
* IdiotPlot: "The Last Strawberry Fun Finger". Not one person considers just splitting the Strawberry Fun Finger in half until the end.
** In "Saving Private Chum Chum" Mr. Mufflin apparently forgets who Chum Chum is and mistakes him for a toy. Although considering that he never remembers what Fanboy's name is (always referring to him as "Purple Kid"), this may very well be justified.
* LoveItOrHateIt: Very much. People love the show for it's quirkiness and lovable characters while others regard it as one of Nickelodeon's worst shows ever.
* {{Moe}}: Yo.
** BOTH of the main characters (three if you count Kyle) are pretty much this as well.
* NightmareFuel:
** "Fangboy": [[http://sharetv.org/images/guide/581984.jpg Suddenly Fanboy doesn't look so cute]]...
** Kyle in "Speed Eraser", where he uses his magic to have Fanboy's hand stuck to the eraser and telling him if he picks up ''anything'' with that hand, it will be erased.
* TastesLikeDiabetes: Yo is a living example of this.
--> "Doesn't Prank Day make you think of rainbows and puppies and ''Chum Chum''?!"
* UncannyValley: ''Everyone'' has their moments where they look.... off. Closeups especially.
* SoBadItsGood: The art style.