Mikey's reasoning for why he should be the leader instead of any of his brothers? Well, he doesn't actually have a reason, he just thinks it'd be neat.
Mikey's face when he takes his first bite of pizza. And his brain subsequently exploding from flavor.
That scene in general, really.
Donny: Should we open it?
Leo: Careful! It may be dangerous.
While waiting for the kidnappers, Mikey and Donny start playing word games.
Mikey: Okay. I'm thinking of something green. Greeen. Greeeeen.
Donny: (Boredly) Is it Raphael again?
Mikey: MAN, You're good at this!
Donnie facepalming, forgetting he's wearing wall-climbing spikes on his hands.
After getting a mini-lecture from Splinter about how there are no "right or wrong" decisions, only choices, Leonardo learns he was chosen as the leader was because he asked for it. Shocked, he asks if Mikey would've been an option.
In response to Donatello geeking out over April and the fact her dad is a scientist in the second episode:
Donnie: This is awesome! That girl's dad is a scientist! I'm a scientist! Oh, she is so gonna like me!
Snake: ...I don't think you're her type.
Leo explains the stakeout:
Leo: For the last time: That building has the same logo as the van that took the family, so if we wait here long enough one of the kidnappers will eventually show his face and when he does we'll make him tell us where they took them.
Raph: No, you have to come up with a better plan, 'cause the four of us standing here with our thumbs up our noses-
Mikey: (looking at his thumbs) I don't think they fit...
April tries to escape the Kraang by faking sickness and attacking a Kraang guard. He doesn't even react when she grabs him or even when she bites him. Then he picks her off his back with one hand, puts her down, and locks her back in the cell with her dad.
April: Okay, I guess we can just sit here.
Just after Raph complains that the van is never going to arrive:
And again when Baxter tries to come up with a name for himself. One particularly funny name he makes up that is just so absurd is "Captain Punch-You-Hard". Another, which Michelangelo admits he likes, was "The Suitinator".
As the Turtles are about to start fighting Stockman, Mikey screaming "WAIT!" and the subsequent shot of the other Turtles and Stockman frozen mid-battle, all looking at Mikey... who just wanted to put the T-Pod away before he started fighting.
The intro itself gives Splinter a good moment.
Splinter: How many times have I told you not to skateboard in the lair?
Mikey:[Exchanges a look with Don] ...none, Sensei.
Donnie spying on April using Metalhead and talking about how she won't notice... and he forgot to turn off the speakers so April hears him. He then tries to cover it up and ends up hitting the megaphone button and embarassing himself even further.
The Shredder learning from Bradford what happened and how he failed his mission:
The Shredder: ...They defeated you with go karts and a water balloon?
Made even funnier when you realize that the Shredder is more confused than angry.
"Doctor Prankenstein". Especially when he gets Leo.
Raph: I can't believe I'm saying this but, 'get it together, Captain! You're our leader, so act like one!'
Leo: That was the anxiety ray talking.
Raph: What, that's it? You're not gonna slap yourself?
Mikey's explanation of where he got the pizza at the end. Double points for him calling them out on their disgust, as pizza from a dumpster still in its box is likely more sanitary than the worms and algae they've been eating before they came up top.
Mikey:What!? We live in a sewer! Now you're clean freaks?
There's a brief view of April's student ID. Apparently when she got it taken, she had braces and glasses, and looked nothing like how she is today. It's rather hilarious.
"Okay, Spike, you'll like this show. It's called 'Does Mikey Bend That Way?'"
Michelangelo tries to offer everyone a pizza milkshake, leading to this exchange:
Donatello: There's no way that can sound any less appetizing!
Michelangelo: I call it the "Pi-Shake"(pronounced "pee shake")
Donatello: (nearly vomits) I stand corrected.
On Leonardo's television show, the episode deals with these adorable pink fluffballs the crew has on their ship. The captain disposes of them humanely by ordering the airlock to open, and the aliens are sucked out while he sits there in his chair with a stoic look on his face, and smiles.
Raphael: You have to be the only one who likes this show.
Upon arriving in Leatherhead's booby-trapped hideout via a long underwater swim, Raph gets this gem:
Raphael: Whew! Sometimes, it's good to be a turtle.
(A stop sign comes from nowhere, slicing through the air between Don and Leo with Audible Sharpness. Raph ducks into his shell just in time to avoid being beheaded.)
Raphael: ...and sometimes, it's good to be a short turtle.
When Leatherhead is subdued and brought to the turtles' lair, one might expect Splinter to (rather sensibly) order him thrown out. Instead, he declares that it is alright to allow him to stay, as it is important to show compassion. Upon being asked if they still need to chain Leatherhead up so he can't get at anyone...
Splinter: Of course. I'm compassionate, not insane.
Why am I the one who has to touchthe weird Kraang stuff?!
After they return from Leatherhead's lair, Mikey explains to his brothers that Leatherhead is "off the chain". When they freak out at him over letting Leatherhead loose Mikey clarifies that "off the chain" means he's calm and reasonable. Which is why Mikey let him loose.
Near the end of the episode, we have this conversation:
Splinter: Leonardo, you are not the first man, or turtle, to make a fool of yourself over a girl.
Mikey: What about Donnie? *gets smacked*
Another from Splinter after he says he understands why Leo didn't tell them about Karai.
Leo: I was worried you'd be mad.
Splinter: Who says I'm not mad? (smacks Leo with his stick)
Bradford laughing at the malfunctioning robot legs that Stockman built for Xever.
"Fix this, or I'll bite your face off." (gets kicked in the face)
When Raph asks Leo if he's going to tell their brothers and Splinter about Karai, we have this little exchange:
Leo: No need, we had a little chat and she agreed to leave us alone.
Raph: Right, because villains always back off when you ask them to. Maybe I'll text the Kraang and ask them to stop mutating stuff.
Mikey can't come up with a fitting name for the large mutant they have to fight. He decides to just go with Justin.
Mikey screaming like a girl (as in a stock girly scream) when the DNA fusion is in the process of creating Justin. The funniest part is that, after showing tanks of armadillo, octopus, jellyfish, and electric eel DNA, Mikey screams at the tank of cat DNA.
Leo: Let's put old mother Hubbard back in her cupboard.
Leo, Raph, and Mikey are arguing about who gets to drive the Shellraiser and Don hits all 3 of them with his bo staff, assigns Leo as the driver, and when Mikey and Raph ask why, Don points out that Leo's the only one who won't use the Shellraiser to hit something for fun.
Leo imitating the Kraang along with April and Splinter's reaction.
Leo: "The ones who are working for this place must punch the card known as the time card into the clock known as the clock of time."
Donnie once again getting the face shaking treatment from Leatherhead.
When Leatherhead asks about the power cell, Donnie's smart enough to back away before Leo answers. It still wasn't far enough, but Leatherhead recovers quickly and pinches his cheek while reasoning that the Turtles did the best they could to defend it (they sorta didn't but they stop Mikey before he corrects him).
Two Kraang talking to each other. They're awfully funny despite being evil aliens from another dimension.
Kraang "I suppose Kraang has once again been foiled by turtles and failed to retrieve that which kraang was to retrieve."
Kraang "Kraang is wrong, Kraang has retrieved it, in Kraang's face."
A Kraang picks up Mikey's nunchucks, twirls them, looks happy, hits itself, and tosses them.
Don is trying to figure out where he's seen the Kraang's insignia before and Mikey repeatedly speculates it's the Olympics. Frustrated, Don yells at the others to leave him alone so he can solve this mystery, which was enough to scare even Raph and they back away. Splinter then walks up and also thinks it might be the Olympics.
And when Donnie yells at them, Mikey leaps into Raph's arms in the background.
The retinal scanner in the elevator:
Female computer voice: "That which is known as access is granted to Kraang."
April: "This just doesn't make sense. If the Kraang want to terraform the Earth, why do they need my dad?"
Leo: "Well, he is a scientist."
April: "Yeah, but he's a psychologist. He studies rats going through mazes. (To Splinter) No offense."
When Stockman is asked why he became a villain, Stockman starts talking about his past hardships and at one point states he built a volcano for a science fair and used actual molten lava which burned down the gym and got him expelled.
Also, when Stockman describes himself as a sensitive, misunderstood child, Dogpound replies with a deadpan 'Well, there's a surprise.'
April's attempts at finding the right ninja weapon.
Splinter: You already possess the Kunoichi's greatest weapon. The mind.
April: Yeah, but when was the last time you saw someone hit a bad guy over the head with their mind?
The Turtles and The Foot Clan attack the Kraang at the exact same time. The baffled reactions of The Foot Clan sell it as well as Raphael being told to be pinched to see if he's dreaming. Mikey obliges, and gets hit for it.
The end of the episode. Wiped out from beating Stockman and his labyrinth, the turtles and Dogpound and Fishface try to start fighting again. Only to say screw it and go home.
Raph berates Leo for bringing Karai into the Shellraiser since she'll see all their technology. Karai sarcastically responds that they're doomed when Shredder finds out they have an ice cream cone-shaped lamp.
Mikey acts like the punching dummy is sentient.
Mikey: *responding to Raph hitting it* You're pretty tough when they can't fight back.
Mikey: *to the dummy when Raph knocks it on the ground* You'll get him next time.
Donnie finally getting to tease someone else for their crush.
Leo: If Karai can pull it off.
Donnie: Why, you worried about your girlfriend? I see why you guys do that, it's kinda fun!
Splinter licking Raph during a demonstration on throwing your opponent off balance.
When the Turtles wonder how they're going to stop the Kraang's plot to terraform Earth's water, Donnie assures them that he has an awesome idea. Cue the Gilligan Cut to underwater, where we see the T-Sub's debut...and that it runs on manual bicycling.
Leonardo: This...is NOT...awesome.
Donnie trying to make the T-Sub go faster...which breaks the engines off, and sends them flying away.
Mikey: Wow, that is fast.
The giant sea monster from Dimension X falling in love with the T-Sub.
Mikey: Hey, we're not that kind of sub!
What really drives the point home are the looks on the turtles' faces. No words can describe that utter shock and disbelief. You just have to see it for yourself.
The turtles training session using each other's weapons. Leo trips himself with Don's bo staff, Raph hits himself with Mikey's nunchucks, Mikey throws Leo's swords in the air and nearly cuts off his feet, and Don pokes himself in the chin with Raph's sais.
Donatello becomes excited after seeing a centrifuge at the Kraang base.
Raphael: If I ever get that excited about a centrifuge, please put me out of my misery.
Raph, Don, and Mikey's attempts at getting Leo away from the wasp egg. They try luring him away with a jellybean, anchovy, and jalapeno pizza, watch an episode of Space Heroes, and Mikey wipes his butt with Leo's signed Space Heroes comic book.
Raph's reaction when Leo starts acting out of the ordinary.
Mikey accidentaly revealing the entrance to the Kraang lair by driving a car off its jack.
Donnie insisting that Mr. O'neil not tell Mikey that he named Newtralizer. And then when Mr. O'neil does anyway:
Mikey: You named something without me?!
"Kraang is that which they call idiotic". That is all.
Raphael trying to put a good word in for Donnie with April at the end is hilarious in how overblown it is. So is Donnie's reaction when it works and she hugs him!
Raph attempting (and failing) to open a door in the Kraang lair, and the turtle's next solution.
Leo: Again, what would Donnie have done?
Mikey: Hmm... Oh! *Mikey spots the Kraandroid, and snaps his fingers* (Donnie had previously opened the door by pressing the Kraandroid's face against the door's scanner, for a second one thinks Mikey has figured this out until we cut to...)
*All three turtles repeatedly ramming the door, using the kraandroid as a battering ram*
And then when the alarm goes off...
Mikey: Donnie's idea was terrible!
Mikey responds to Leo's question about whether or not anyone's seen Donnie with a long description of a dream he had in which he and Donnie were "Rodeo Detectives", complete with Imagine Spot of them in cowboy costume, who solved the mystery of who stole the "Buckaroo Diamond." It was the clown.
In Space Heroes, Captain Ryan's plan to save his ship and crew is crazy, defies all logic, is illegal in 16 Solar Systems, and doesn't believe his mother would approve. When his plan fails, he tells his subordinates to abandon ship and when one of them salutes him and says it's been an honor, he slaps him and tells them to get out while they still have time. It also counts as a heartwarming moment for Captain Ryan of all people.
Also note that Ryan somehow slaps his subordinate from across the room.
If you don't see it as Nausea Fuel, Bat Kirby regurgitating a rat and some plastic cups for April to eat can be this along with April refusing to eat and telling him to get her some real food. It can also double as a heartwarming moment in a somewhat twisted and disgusting way.
Mikey's fly costume.
The fact that he genuinely believed his brothers when they said they dressed him up as a superhero.
Mikey's plan to track the invisible Kraang ship. Put honey on the ship so it'll attract bees and then follow the bees. Everyone, even Metalhead who wasn't remote controlled, turned and glared at Mikey for the sheer stupidity of his plan.
You can notice in the background even Mutagen Men in his tank is glaring at him.
Leo asking Splinter how to lure a lost pet back and intially uses a cat as an example freaking out Splinter.
IT HAS BUTT CANNONS!?!
Mikey calling the mutated Kirby "Wingnut", then Donnie telling him not to assign him a monster name.
At the very end of the episode, when the squirrel takes a few sips of the spilled mutagen, it stops and whirls around, posing for the camera in the exact same stance as the dramatic chipmunk video. It even plays the same musical sting as the camera zooms in.
Mikey wonders if Kirby would bite April, turning her into an undead vampire. Needless to say, Donnie is not amused.
Splinter asks who's going to step up and scout and find the Squirrelanoids. The Turtles opt to use Metalhead instead.
One of the Squirrelanoids jams itself into Raph's mouth and the others strap him to a table and view his X-Rays and Donnie states they have to perform surgery to remove the Squirrelanoid before it can duplicate and takes out a buzz saw powered by kinetic energy and Raph struggles to get free and the other turtles laugh.
Leo, after hearing Mikey suggest that the Kraang are building laser burritos says that after they finish the mission, they'll get Mexican pizza with a cheeky grin.
Mikey and his frankly impossible shadow puppet distraction.
The Kraang's descriptions of the shadow puppets are also pretty hilarious.
The Foot Robots have difficulty on the ice, and then quickly adapt. It happens twice.
Casey and April's mid-fight banter.
Casey: You got some rink rage, red!
April: You should see me play ping pong.
Donnie's cell phone goes off in vibrate mode on a mission. What makes this more funny is that he clearly learned his lesson from the last infiltration mission about being more discreet, since it didn't ring.
Mikey accidentally causing danger with Kraang weapons. twice. He even makes the same sheepish expression afterwards.
Casey faints when he meets Splinter due to his fear of rats. April revives him with a slap across the face. Raph makes fun of him for it and then Mikey holds a cockroach in front of his face scaring Raph into withdrawing into his shell.
Raph: The kid's afraid of rats.
Mikey: Kind of like you and cockroaches, huh, Raph?
Mikey's pizza at the end has anchovies, pepperoni, and mushrooms. The others are not amused.
Donatello and Raphael try and get Casey to calm down after he gets spores on him. Casey then sees Donatello and Raphael, as they're telling him he's going a little nuts, be covered in rats. Rather spooky, but very comical.
Mikey jumping on the spores Super Mario Bros. style.
After Raph gets spored, Mikey tries to comfort him by giving him a hug. The problem is that Raph sees Mikey as a giant cockroach. He then pukes from this scenario.
The port-a-potty scene for those that don't mind a small dose of Toilet Humor. Mikey being the only one who can open it is funny enough, especially when he starts boasting and Donatello gets irritated... but watching Donatello open it several times in a row, complete with a fart noise playing EVERY time gets increasingly funnier.
Irma asks if April found her by following the aroma of rat feces and is about to describe what they smell like only to get interrupted by April and Casey.
After defeating Leo during a training session, Splinter hits the other turtles while blindfolded and says it's easy to sense loudmouths.
Mikey playing as mutant rat bait with a piece of cheese on his head.
In the game Trick or Treat Tussle, on Nickelodeon's website, Mikey's Halloween costume is Spongebob and he attacks by throwing krabby patties. Raph is a fairy princess because he waited until the last minute to find a costume, Leo is dressed as Captian Ryan, April is dressed as...the turtles, and Donnie's costume is from the renaissance era and he attacks by playing his lute.
Some of the concept art has a good deal of humor, particularly in Casey Jones'◊.
First Psychotic Human Friend!
"The Final Slice," a Nickelodeon flash game is full of hilarity particularly because of how the derpy art style emphasizes how goofy these brawls for pizza slices are.