"I'll trick them into sitting in this electric chair. If they survive, they're FAIRIES! If not, I HAVE TENURE!"
This hilarious exchange-
Cosmo: Hi Timmy, look, I'm a lawyer! *Poof* Now I'm a fireman, WHEEEEE! Now, I'm just a simple fairy/lawyer/fireman, but Jorgon misses the point, there are many redeaming qualities to Timmy. Isn't it true that you also wished for new shoes, sunglasses, butlers and shiny teeth?
Cosmo: Wow, what a selfish punk! The defense rests.
Wanda: That was your laser targeted defense?
Cosmo: I'm a fireman, not a laser technician. *Poof* Now I'm a laser technician!
And then after Timmy's punishment is announced:
Cosmo: *Poof* Don't look at me. I'm just a coal miner.
"The good news is I named my nickel Phillip!" "What's the bad news? "It's a GIRL nickel!"
In the episode where Timmy wishes every day was Christmas, causing the other holiday mascots (all male) to get ticked off at him. In one scene, they rush to attack Timmy but stop short when they come underneath some mistletoe. They all immediately start shaking hands and saying things like, "You're a nice person/I like you as a friend" before resuming the chase.
"The Big Problem":
Timmy: "What's going on? You said you just couldn't grant me more wishes. I didn't know you'd have to leave me too." *cries*
Cosmo: "We didn't know that either! Apparently the other thing I'm chock full of is not knowing stuff."
Vicky loses Timmy because he wished himself older and frantically tries to find him with "Have you seen this twerp?" fliers.
In "That Old Black Magic", Dad, after telling Timmy not to step on cracks, swears to go back home only when each and every crack of Adrenaland is repaired. When he sees a worker with an exposed gluteal cleft, he starts chasing him while holding a bucket for cement and a trower.
The horrible bike that Timmy's dad made for him, complete with a bag of manure for a seat.
In the Halloween Episode, we have this exchange:
Timmy's Dad: I'm going as your mom! *pulls down a mask of Timmy's Mom's face*
Timmy's Mom: I'm going as your dad! *pulls down a mask of Timmy's Dad's face*
Timmy wishes for his parents to have superpowers, so they can get their work done without getting worn out. Mom and Dad soon realize they have powers, but decide to keep them a secret from Timmy based on a reading a comic book. One moment later...
In "Mother Nature", Dad decides that since Mom is now working as a weather person, he has to be be both "Mom and Dad". Unfortunately, his idea of being two parents is using a puppet that looks like Mom. A puppet he has arguments with, to which Timmy says, "No amount of therapy will ever make this moment ok."
Also, everyone's reactions to Timmy's mom in a fireman outfit:
Mom Puppet: HEY!
Timmy: (Passes out)
Cosmo & Wanda: Hey!
From Abra-Catastrophe: "When this is over, I'm wishing for a world without puns."
Made funnier with Cosmo and Wanda's commentary track, where they say the same thing.
"I thought you said 'Plastic surgery'!" as said by Cosmo, complete with breasts, during a rapid-fire series of clips provided by Cosmo's mother to discredit her son's relationship and godchild assignment.
Also, Cosmo: "I'm keeping them" (referring to the gag boobs)
Timmy's Mom *bawling* "EVERYTHING I TOUCHDIEEEES!"
"Pants are for squares!" "Studying is for squares!" "Electric bills are for squares... like pants!" "Hygene is for squares!"
"SCRAMBLE THE FAIRIES!"
"Sir, we didn't really need to scramble the fairies."
"I LIKE TO SCRAMBLE THE FAIRIES!"
"Sir, we usually just poof to Earth. You didn't have to destroy the bridge."
"I LIKE TO DESTROY THE BRIDGE!"
"What flammable-" *BEEP* "PUDDING!"
"I like making the buzzy noise!"
The entire sequence during Abra-Catastrophe when Crocker disguises his van as an ice-cream truck. Complete with Pop Goes The Weasel playing in the background and Crocker laughing maniacally.
Made even funnier when Crocker then turns the van ice-cream truck into a spinach truck to scare children away. "AHHH...SPINACH!!" And, then cue a whole bunch of sailors. "AHOY! SPINACH!"
When Timmy finds out that Crocker used to have fairies himself as a kid (who turn out to be Cosmo and Wanda), and he does one of Crocker's "FAIRY GODPARENTS!" spasms upon realization.
Timmy: If I do that again, hit me.
(Cosmo produces an oar)
Timmy: Not now!
Also, "Must...Resist...Stupidity impulse." *Poofs a Jack-in-a-box in front of him* "Not...resisting well!"
Timmy has run away from home and joined a carnival
Wanda: You can't stay a carny forever, Timmy.
Cosmo: Yeah, you don't have the experience! You've never even been to prison!
In "Abracatastrophe", a Running Gag is Wanda getting brown stuff thrown in her face by Bippy, a monkey.
Wanda: PLEASE be mud...
"Pipe Down." Any character screaming and then exploding. Funniest example is Timmy's dad. Timmy breaks some important stuff, Timmy's dad screams angrily, but no sound comes out, because Timmy wished for silence. Timmy's dad tries again and Timmy puts a hand to his ear as if to say, "I can't hear you!" Timmy's dad screams again with his hair igniting and his face turning purple, before he explodes.
Cosmo: Wow, that's violent, too. Didn't they have censors back then?
And made even funnier by the fact that, each time, Wanda or Cosmo's head was blocking the violent scene. So no, Cosmo - no, we don't see violence like that on TV anymore.
That part when they go into a parody of Speed Racer. If you watched the anime, you'll laugh a lot once those over the top explosions and facial close-ups with Oh Crap expressions kick-in.
"TAXES ARE TOO HIGH!"
Deep Toot. I'm still laughing just thinking about that one.
"WHO ARE YOU, DEEP TOOT?!"
In "Just the Two of Us," Trixie, suddenly becomes completely insane despite being relatively sane before, completely loses it and attacks Timmy after he breaks up with her when they're the last two people on Earth. Timmy's following line is the best.
Timmy: "Note to self: Never break up with a girl in the violent gardening tools section."
When Timmy wished his parents would get some friends, which leads to Cosmo and Wanda becoming Mr. and Mrs. Turner's friends, they realize that they've been neglecting Timmy (more than usual), so rather than blow off their dinner plans with Cosmo and Wanda, decide to be as rude as possible to drive them away.
Mr. Turner: Ooh, Wanda! Have you gained weight? A loooot of weight?
Wanda: Uh, no? So, uh, how's the coffee here?
Mr. Turner: You tell me!
(Throws hot coffee in Wanda's face)
Later when he asks her again:
Mr. Turner: Have you gained weight?
Cosmos: A loooot of weight?
After Cosmo and Wanda disappear to discuss what to do about the Turners, the Turners wonder where they went:
Mrs. Turner: Hmm, they've been gone a really long time.
Mr. Turner: Maybe they're dead.
Mrs. Turner: Quick, let's establish an alibi!
From "Lights... Camera... Adam!"
Adam West: How do you say this word?
Guy Playing Cleft: Chin.
Nega-Timmy walking into Crocker's class room and then just hissing in his face.
F,F,F,F,F,F,F,F,F,A For AJ,F!!!!
"And now, I think I'll run a marathon! But first: FAIRYGODPARENTS!FAIRYGODPARENTS!FAIRYGODPARENTS!"
In the same episode, they turn "I'm off to run a marathon." into a sort of running gag... literally!
From Timmy The Barbarian-"Mt. Fluffy Bunny! Wait, that's not very scary. Mt. Disco! No, wait...Mt. PAIN!"
Also, Jorgen Von Strangle skipping over all the more cheerful parts of the story much to Timmy's annoyance.
"And then Cosmo...tripped on a bug!"
"Wanda! Nag! NAG LIKE YOU'VE NEVER NAGGED BEFORE!"
The entire episode, really.
In Something's Fishy, Timmy finds out that his Wet Willie gear is useless underwater.
Timmy: Hollywood lied to me!
Cosmo: Hollywood lied? Curse you, movie critic Gene Shalit!
And later, when they find Atlantis...
Cosmo: Thank you, movie critic Gene Shalit!
The fact that Cosmo somehow managed to sink Atlantis nine times.
Wanda: You sank Atlantis nine times!? Where was I when this was happening?
Cosmo: I have a whole secret life that you know nothing about!
The episode where the Turners moved to a "Stepford Wives"-esque community had the bit where all the zombified people (plus Cosmo and Wanda) tried to get Timmy to get drink the brainwashing milk... then Crocker pops up, saying in the same deadpanned zombie voice "Fairies, faries..." For some reason, that make this troper laugh.
From "Fairy Idol", after Chester wishes for the penguins to be warmer, the earth basically enters the sun.
The sun: HEY! A little space?!
Then, at the very end, when Chester wishes everything back to normal, the earth moves farther away from the sun.
The sun: ...Was it something I said?
Crocker's reaction upon seeing Cosmo, Wanda, Poof, and Jorgen in the second part of the Wishology special is downright hilarious. He spazzes for 15 seconds before growing exhausted and panting heavily.
Wanda: (panicked) Cosmo! Timmy's parents found Poof!
Cosmo(also panicked) Oh no! Those people have no idea how to raise a child!(notices Timmy glaring) No offense, Timmy.
Timmy: Don't worry Jensen, this battle will only take 2 minutes.
*Cut to all of them in a torture chamber*
Wanda: You were close; the battle took 1 minute 40 seconds.
Timmy:(To Jensen who is hanging right next to them) See Jensen, have I ever lied to you?
The episode where Timmy's mom turns their house into a bed and breakfast because Timmy's dad quit his job to become the sock monkey king. The guests are Crocker, Dark Laser, and Tootie, who are trying to capture Timmy's fairies, destroy him, or kiss him, respectively. At one point he ends up in his parent's bedroom and tells them that the guests are after him. Their responses:
Timmy's Dad: Do they want to buy my sock monkeys?
Timmy's Mom: Do they want to stay an extra night and give me even more moolah?
There's a bit where Timmy pushes a button on Dark Laser's chest turning his body into an inflatable raft. When Dark Laser tells his henchmen to chase Timmy they pull out paddles and begin dragging him across the floor.
Also, this exchange at the beginning of the episode-
Crocker's Mother: Make a wish, Denzel.
Crocker: (Deadpan) I wish I could get out of this highchair.
While "Lights Out" might have had its scary moments, it also had some pretty funny moments too, made even better by the fact that the viewer couldn't see what was happening on-screen...
And the only thing that we really could see was their eyes.
The entirety of "Food Fight".
In "Crocker Shocker" when Timmy needs the last of his fairies' magic to teleport to Earth, Wanda squeezes out the remaining magic in Cosmo's body by putting him through a wringer, then putting him on a clothesline and beating him with a tennis racket.
Timmy's Dad becoming a Criss Angel parody in "Dadbra-Cadabra".
As said parody he also wears a pair of tight pants that make him incapable of walking normally, so he wobbles looking like a South Park character.
In "Farm Pit" a tornado whisks Cosmo, Wanda, and Poof to Cleveland. Cosmo thinks that they're in Oz. Hilarity Ensues.
"Balance of Flour." This line said in an Arnold Schwarzenegger voice: "More. Good! MOOORRRREEEE!"
In "Fairly Odd Pet" when it's mentioned that Sparky could be sent to the pound, Cosmo believes that the pound is a place where they pound you with a mallet and convert all your money to British pounds, and with the USD to GBP exchange rate Sparky will lose 30% of his portfolio and will never be able to retire.
When Timmy wishes that the kitchen was full of cats to trigger his mom's allergies, his dad thinks she's a monster and jumps into a barrel of push pins he stole from work. He lampshades this, saying "Sometimes even I marvel at the terrible choices I make."
In "Turner and Pooch" Crocker goes through several different disguises while stalking Timmy, but when he can't get an ice cream man disguise he goes for the next logical choice: a vampire he calls Count Creamery.
Timmy's Dad: Make my wife disappear? Cosmo:Isn't that illegal? Timmy's Dad:Not if you make the police disappear!
When Timmy's Dad asks Cosmo to wish that Dinkleberg never existed against the latter's advice, it results in a Non Sequitur Causality where society has been destroyed and Timmy's Mom is a two-headed dragon.
In "The Terrible Twosome" when Poof and Foop begin working together, he suggest they call themselves "Poop", then "Brangelina".
Their pranks on Crocker, which are turning his churro into a stick of dynamite, giving him a box of chocolates full of scorpions, then bringing his swan boat to life and having him ride into the mouth of a one-eyed sea monster.
Foop going through his "terrific twos" and hating it.
In App Trap, we have an exchange that sums up the SmartPhone perfectly
Crocker's excuse for impaling Principle Waxelplax on the rear with a fork. "It's cupid's fork...of love...I LOVE YOU!!!"
"This is so sudden. And...unwanted."
From the storybook All Washed Up!:
Wanda: There are four basic elements: earth, air, fire, and— Cosmo: JELLY BEANS!
In one episode, Timmy is in class when something goes wrong and makes a wish that he can get out of class 'inconspicuously.' Cosmo poofs a pair of rockets onto his desk and Timmy shoots out through the ceiling, getting everyone's attention.
Wanda: (To Cosmo while Timmy is flying through the air and screaming) IT MEANS 'WITHOUT BEING NOTICED!!'
After that Crocker notices the burn marks on the floor and assumes Timmy exploded, saying "Hey, Turner exploded! That's one less mouth to teach!".
From the video game, Jorgen giving off a sponsor before the final boss:
Jorgen: Brought to you by Smark's Brand Magic Wands: The Perfect Wand for the Perfect Fairy.
Even better, one of the panels you can get Vicky to jump on during that boss is that exact advertisement.
Cosmo on double-jumping: "It's twice the fun, and only two-thirds the calories!"
The following gem:
Cosmo: Let's split up! I'll take Timmy, Wanda, Poof and Cosmo!