From issue eight of the original series, Beast takes his uncomfortably small shoes off in a cafe full of beatniks, who begin reacting in an astonished fashion. They then proceed to carry him off, declaring his feet a sensation. He has no idea what is happening.
Not to mention said beatniks drawing faces on his size EEE soles.
Astonishing X-Men was full of these from the beginning.
Kitty accidentally being late to the assembly Emma is holding for the students in the Danger Room.
Emma: This children, is Kitty Pryde, who apparently feels the need to make a grand entrance.
Wolverine sitting on the foot of Cyclops and Emma Frost's bed asking the former "whatstage of grieving" their sleeping together is. Followed by him getting blasted out a window.
Their first mission, rescuing the hostages from Ord, involves Kitty phasing people through the floors under said Ord's nose.
"Who are you talking to?" *soldier looks out an empty window* "My swim coach..."
Lockheed popping out of nowhere and flaming Ord in the face. This leads to Wolverine thinking he should be team leader.
The party they had to literally crash to rescue? It was a fundraiser that Frost's family had supported for "generations," and now that she's a public mutant she isn't invited. How she convinces the organizer to let her back in the loop? Threatening sexual obsession with Leroy Neiman's artwork.
Beast is analyzing a sample of "Hope", a "cure" for mutation, and is seriously considering using it. Wolverine starts a fight with him over it that spills through a wall. One student's observation: "So, what - the teachers spend all their time here trying to kill each other? This place is so cool."
Emma Frost being a teacher of "ethics."
When they attack Genetec, the source of the Mutant "cure," Scott is shot and bleeding out. His hallucination is hilarious.
The team is facing Ord for a second time, coming up with a plan that will probably involve his eyes and other "soft" parts. But before they can finish it, Beast, Logan and Frost are all surprised because Colossus, who has just returned from death, is standing behind Ord. That look is priceless. Ord assumes something else:
"Is that dragon thing behind me?"
John Cassaday's facial expressions totally sell the scene.
When asked how they know it's Colossus they just found, Emma tells Agent Brand she read his mind, Beast tells her he checked his DNA, and Wolverine simply says "I smelled him." Beast chimes in with "I did that, too."
Colossus throwing Wolverine in a Fastball Special is his first act out in the sunlight. Doubles as a CMoA.
"You bite, I'll heal. I pop, you won't."
While the team is fighting a big monster in downtown New York (to which The Thing yells is supposed to be the Fantastic Four's gig), each page is panels of them with their internal monologues about various emotional struggles. Then we get to Wolverine, who has 3 panels of nothing, followed by:
Wolverine: I really like beer.
After the Danger Room has been shut down by becoming sentient and leaving, Logan takes a bunch of new students down there for fight training. When one asks what the danger will be, Logan turns off the lights. One long panel of darkness, followed by a second. In the second, "shinkt."
Cassandra Nova, controlling Emma, regresses Logan to his childhood as effete, pampered rich boy James Howlett. How is he awakened? What else - A beer.
The highlight is probably his prayer when cornered by a feral Beast: "Dear God, I promise that if you let me live I'll be nicer to the poor, unless you don't like them for some reason and that's why they're poor."
To awaken Beast from his feral nature, Blindfold hands him a ball of yarn. One that is chemically treated to restore his mind.
Also from the "Torn" arc, when Kitty and Peter have sex for the first time, and Kitty ends up falling through the floor into the TV lounge directly below Peter's bedroom.
Kitty: I can't believe I phased just then. That's never—it was all your fault.
Peter: I like to think so, yes.
And the next morning, at breakfast, Logan just looks at the two of them and says, "About time."
The Once More with Clarity page, when the mental dialogue is added in when they are discussing their plans. Especially Kitty and everyone's reaction to her.
Kitty: I object!
Piotr: Is not courtroom drama, Katya.
"Can I help you?" "Are you a beer?"
Emma deleting the memory of bad guys: "You feel no pain. You will go straight to a hospital. Remember nothing of this place. And every time you hear the words "parsley", "intractable" or "longitude", you will vomit uncontrollably for forty-eight hours."
Cyclops: "My girlfriend is very weird."
This exchange between Wolverine and the Thing:
The Thing: Didn't they come up with a cure for your kind?
Wolverine: You got a problem with mutants?
The Thing: I meant Canadians.
When Wolverine nearly kills her during training, Armor curses at him in Japanese. Wolverine immediately responds in Japanese to her horror.
"Cyclops—Scott Summers. Leader of the X-Men. Owner of a jetpack." After literally decades of the same "optic force beams" intro blurb, we finally get an awesome (and hysterical) new one.
There are many, many moments in Wolverine: First Class, usually courtesy of Kitty Pryde.
Kitty: Actually, yeah. I was wondering... How long does it take you to get your hair looking so good?
Thor: Mine... hair?
Logan gets some in too, of course:
(Robots attack as Logan's trying to watch hockey.)
Logan:(pops claws) Gotta warn you flamin' robots... I'm the best at what I do. And what I do is — (as he destroys the robots) WATCH HOCKEY! WHEN I FEEL LIKE IT! FOR AS LONG AS I FEEL LIKE IT! It's my moral right as a Canadian.
Jean: I must confess, infuriating and arrogant as Gambit can be... those eyes, that grin, the body — it takes a girl's breath away.
Cyclops: Oh, really? When next the opportunity presents itself... remind me to drop a truck on him.
Professor X: Cyclops.
Cyclops: A big truck.
Professor X: Cyclops.
Cyclops: A really big truck.
Professor X: Cyclops!
Of course, this is just after we find out that Cyclops has gone to the trouble of building a robot double of his girlfriend, programmed to explode when Gambit kisses it. This was presumably intended as a form of aversion therapy.
Mind you, that's a boysenberry pie charged with Gambit's energy. (Don't worry, Rogue was in her "stolen Ms. Marvel's powers" phase, so she wasn't hurt. Just pissed.)
In the second New X-Men series (about new students at the Xavier School), Elixir, a mutant healer, discovers that his powers can kill as well and doesn't handle the discovery well, turning his golden skin black while he broods about it. During a psychic conference with the other senior X-Men, Kitty Pryde brings her concerns for his well-being... it turns out she needn't have worried◊.
Rockslide. Just... Rockslide.
Or if you need specifics, try The Quest for Magik or To Serve And Protect. The former is a pretty creepy story, and yet he still manages a CMOF in almost every appearance.
"Welcome to our Brotherhood."◊ Magneto's totally-aware-of-the-irony smirk is hilarious, but what makes the gag is the looks on Cyclops and Madrox's faces, and Layla behind them, trying her damnedest not to cry laughing.
In a What If? story where the all-new, all-different X-Men never existed, the original X-Men plus Havok and Polaris still go to space to the Starcore space station and are about to make the fateful journey back into Earth (in the mainstream universe, this is where Jean Grey became possessed by the Phoenix Force). Keep in mind Polaris wasn't with the X-Men when this happened. Just as Jean is about to take matters into her own hands, this argument breaks out.
Polaris: Will you two shut up!? I can bring this shuttle down to Earth without the computer, without piloting skill, without even leaving the shielded life cells! I have magnetic powers, remember? Sheesh!
X-Men (2nd series) #75 had several great moments. Cecilia Reyes wearing a Wasp costume reject Beast had stolen from the Avengers. Cecilia acting like an ER doctor towards a blood covered Wolverine (she IS a doctor by the way). Cecilia's face when dropping in front of a demon. Also Marrow's when Maggot uses her for a fastball special. Finally Cecilia Reyes destroying a magic demon artefact when she drops on it with her buttocks.
In the Second Coming crossover, members of the "X-Club" (team of scientists put together by Beast) are sent to an alternate future to save the world. Their plan involves using a cat as bait to lure away mutant-hunting robots, and they eventually succeed... only to discover that this "future" was a simulation, all done to trick the X-Club into synthesizing a "cure" to wipe out the X-gene from all mutants. X-Club member Madison Jeffries's relieved response is, "You mean... the kitten didn't die?"
During the team's first encounter with Alpha Flight, they're on the run in Calgary. The team is set to meet at a rendezvous point, but Wolverine, Nightcrawler, Banshee, and Storm are missing. Cut to Banshee shopping with Storm. Granted, it's so that they can disguise Storm who sticks out like a sore thumb, but still.
For a time, Wolverine operated in Madripoor as "Patch", which involved him wearing an eyepatch and taking no other disguise precautions. Throughout the "Gehenna Affair" storyline, people keep revealing that they've known Patch is Wolverine all along, but Jessica Drew explains why nobody told him: "When somebody with claws and a temper wants to believe he's fooling people, well... no one wants to be the one to say, "Hey, Wolvie, what's with the stupid eyepatch!" Not coincidentally, this was written by Peter David.
Kurt: "Figures—We get away from the Hellfire Club with our skins intact, only to get trashed by one of our own! Oi-flipping-vey!"
Iceman and Angel #1: The eponymous duo are going up against "GOOGAM, THE THING FROM PLANET X!" and wonder where the Avengers, Fantastic Four and military are when there's a giant monster trashing Manhattan. The Avengers: fighting Kang. The FF: fighting Annihilus. The military: um...
Namor: For the last time, I can't surrender! This isn't an invasion of your surface world! I just wanted abagel! We don't have them down there! Imperius Rex!
Cyclops #1: Cyke's day has been vastly improved by the chance to loosen up... by taking down the Circus of Crime, at one point pulling a Hero Stole My Bike and leaving a note with an apology and phone number.
Princess Python: We don't exactly look like the kind of people who care, now do we? Cyke: You look like a dollar store Cirque de Soleil, lady. C'mon, walkie-talkies? Are you supervillains or mall cops? [later] Cyke's Internal Monologue: So their boss is rich, old-fashioned and needs a lot of obsolete tech nobody else wants. Doesn't sound like anybody I ever heard of. Who is he, the Mad Hoarder? Baron von Antiques Roadshow? [at the end] Xavier: News reports of a supervillain crime wave with suspected mutant sightings, SHIELD agents inquiring whether one of my students has gone rogue... and a Mr. Herman has been ringing the phone off my desk demanding to know what I've done with his bicycle. What on earth have you been up to today?
Every single panel of Doctor Nemesis in the X-Club miniseries. Especially after he gets the starfish.
Nemesis: Eat viral liquefaction, unethically cloned carbon waste! I'll put my science in you! I'LL PUT MY SCIENCE IN ALL OF YOU! Starfish: I have no idea what I'm saying.
X-Men #9 (v2): Beast, in the middle of a fight after Wolverine growls, says "Logan? I realize you're having trouble holding onto your ever tenuous grip on humanity, but "grrrr" falls somewhat short of articulate." *Wolverine launches himself at an enemy behind Beast* "Of course I'm a firm believer in free expression!"
There's a glorious moment in an earlier episode where Master Mold stands up and attempts to stride out into the world... and is promptly halted by his power cord, which is still plugged into the wall.
The Christmas Episode begins with Jubilee, Rogue, and Scott decorating a Christmas tree while singing "Deck the Halls." Scott hits so many wrong notes, you can almost hear his VA deliberately messing up the song.
Later, Jean and Gambit are the ones in charge of the food. Hilarity Ensues.
Narm: Cable in Beyond Good And Evil part 3. While hunting Apocalypse in ancient Egypt, Cable sees his teammates engulfed in a bright flash from a room away in a tomb. His reaction after he storms into an empty room to see his teammates laying on the ground is unintentionally hilarious. "WHAT HAPPENED?!?!?!"
In "Days of Future Past, Part 1," Xavier reads Bishop's mind and the memories are displayed on a computer screen for the X-Men to watch. After some clips of a Bad Future, the screen displays an older Wolverine.
Wolverine: At least I don't lose my hair.
During Magneto's attack on a chemical plant, he briefly muses on how much Charles Xavier's appearance must have changed over the years:
Magneto: I wonder how you look, Charles, after so long? Perhaps, a toupee?
In "The Dark Phoenix Saga" part 3 episode, Rogue has to catch the X-Men that gets knocked off by the Dark Phoenix.
Rogue: What is this? "Catch the X-Men" Day?
In the first episode, Morph's channel surfing and amusing himself by turning into and imitating someone from each. His take on Senator Kelly:
In the first episode, Hank is preforming a lecture at the college he's working about enhancing the intelligence of cephalopods (squids basically). However none of his students are buying it and aren't doing a good job of holding back snickers. Once Hank gets the call he tells the students he's leaving the squid in charge of them. Which causes them to start laughing, until the squid tells them to quite down.
While Scott and Logan are playing pool in episode 4, when Scott's about to clear the table (again), we get this:
Logan: No way Summers, you are not clearing the slate on me again! Stop! (tries to stop the ball by blowing it in another direction, with his breath)
Scott: Look I know your full of hot-air but that's not gonna work. (despite Logan's efforts the ball lands in the pocket) Told yeh.
During episode 9, while Scott, Logan, Storm and Hisako are looking for Emma. They come across what appears to be a secret door. Logan tries to muscle it open, only for Scott to stop him, and find the button to open it a second later. Logan's pouting-face is priceless.
Storm: Come on Logan, put those overgrown toothpicks away.