Mario Falling asleep from the extremely long "short versions" of the stories.
Reading Bowser's diary, and revealing that he hopes that Peach legitimately likes him.
"And...oh dear! Who put that thing in the story?"
At one point in Crystal Palace, a bunch of Duplighosts try to mimic Kooper and end up mimicking completely different characters, like Luigi.
"BLEECH! WHERE DID YOU LEARN HOW TO COOK!? TRUCK DRIVING SCHOOL!?!"
The result of feeding Gourmet Guy a bad cake. As in, a "cake" made entirely of salt and uncooked eggs, or burned strawberries, or my favorite, just detergent.
It's enough to make one suspect that they allowed the selection and usage of non-recipe specified "ingredients" just for players to get a quick laugh out of results like this. And it's all the more hilarious.
And if you utterly screw up the cake, he mutters about you trying to poison him.
Kammy when she sees Peach disguised as a clubba: "Mmm!! You there! You're doing a fine job."
In the very next line of dialogue, Kammy deduces that the Clubba is actually Peach in disguise because the Clubba smells too nice.
"You know what I just realized? I hate the desert! Yup! Sand gets in my eyes so I can't see. I feel like I've eaten a couple pounds of sand, and my feet itch. I'm freaking out here!"
"Ah, yes! Some more sand and some more cacti! How do you stand such a boring landscape? Look, when I signed on for this adventure, I was under the impression that there would be no boredom involved."
"You know, there sure are a lot of rocks in the desert. Before I came here, I thought there was just sand. But there are rocks, too. Whoopee."
"So hot... I feel dizzy... Where are we going again? Who are you, anyway?"
"So blue...the desert sky... They ought to call it... 'Big Ol' Super Blue Sky'!"
After you thrash the Goomba King and his servants, Red Goomba and Blue Goomba, they retreat to inside his fort. Listening at the window, you hear how the Goomba Bros. hid an important switch where no one will find it...outside.
Paper Mario: The Thousand Year Door
Luigi's partners telling what really happened, as Luigi fudges his stories to make him sound not so pathetic. That poor Blooper.
Poor Blooper? What about the Bob-omb who had to see Luigi in drag?
There's a scene in Paper Mario The Thousand Year Door where Mario has to go through pipes to escape a locked room. Par for the course? Of course, for Mario. But the catch? Said pipes are in a toilet. No matter which of Mario's partners you have with you on the other side, their reaction is priceless—but Flurrie's is probably the best:
Flurrie: I should like to request that we never do that again.
IIRC, Koops says something along the lines of "so THAT'S what plumbers do!" Also:
Koops: X-Nauts? Sounds like tissues... to the extreme or something.
Similarly, each time you run into Ms. Mowz, she gives Mario a kiss before leaving. Each partner's reaction is worth hearing.
Goombella: Ms. Mowz was here before, but I think she took the next train to Floozyville.
"You rang, dude? I mean, sir? You rang, Sir Grodus, dude? Grodus? Sir Grodus, sir?"
Also this exchange at the beginning of the game:
Goombella: Professor, he's Mario! You know, the famous one!
Prof. Frankly: Oh, I'm sorry. I'm such a bookworm, I haven't a clue about what's "hip" right now.
Yoshi: Oh man, the old monster-beyond-the-town-gate thing? Isn't that kinda cliched?
Made even funnier considering he only hatched in the last chapter.
I'm surprised that no one has mentioned the Bowser interlude where Bowser meets Lord Crump in Twilight Town.
Any of the Bowser interludes, especially the ones where you need to control him through mock versions of Super Mario Bros. levels.
Bowser—Extra Lives = ∞
"Great, just great. Now I look like the huge, mighty king of GUYS WHO TALK TO POSTERS!"
Bowser's epic battle against Rawk Hawk for his Crystal Star:
And, of course, Bowser's reaction to the news that he has been beaten to yet another Crystal Star... by Luigi.
"Swimming. I was swimming."
In the first interlude, Bowser can listen to two Hammer Bros. in a conversation. The first one starts blabbing about how he caught Bowser mooning over a picture of Princess Peach, all while the other one is telling him to shut it. His reaction when he turns around is pretty damn hilarious.
"I'm not funny, sir!" "He's not funny, sir!"
When Kammy Koopa tells Bowser that Mario is in Rogueport, she expects a huge reaction obviously for her scouting and hard work. She gets:
"Pfft.... what do I look like? His baby-sitter?
At the Great Tree, Kammy and Puni Elder get into an argument. Bowser has one of two thoughts that the player can choose; "You're BOTH too old!" or "It's hag vs hag! Awesome!" Regardless, Kammy will ask Bowser why it looks like he's dying to say something.
"You got it, Haggy!"
When Bowser goes to Poshley heights, most of the characters are either oblivious, in denial, or terrified of him. But if you talk to one of the penguins, he is hardly impressed.
"What's that you say? You're a great and evil king? Suuuure... Listen, buddy, I think you've been spending too much time in the sun." or something like that.
When visiting Glitzville, try answering the pay phone. You might get a weather update.
Phone: Weather in Glitzville is sunny, with a chance of more sun. It's above the clouds, stupid.
How about when a guy calls and says "Hello?" repeatedly?
The Nintendo Power guide for the game is actually pretty funny in parts.
Two moments in said guide that particularly stand out:
(After receiving the threatening e-mail in Chapter 3) "Mario then proceeds to go on a rampage and whack everyone in the locker room with a steel folding chair...no, not really."
(When the Russian-accented Bob-ombs reveal their giant cannon to fire Mario to the moon) "Those of you who grew up in the '60's, feel free to hide under a table."
Anytime you fight (and win) in the Glitz Pit with Yoshi.
Yoshi: Ah ha ha ha ha ha ha ha ha! How'd that floor taste?
Doopliss impersonating Mario.
For people who looked it up or replayed the game, when you try to guess Doopliss's name but use an uppercase "P" instead (since the lowercase "p" is missing) You'll get "Doo Pliss? Hahahaha! Who'd name their kid that?"
After his defeat, he ends up joining the Shadow Sirens, and becomes the replacement Butt Monkey of the group. By their final battle, the guy who forced you to take a long back-and-forth journey just to learn his name is begging to be called Doopliss, rather than "freak-in-a-sheet".
The funniest part would probably be Doopliss freaking out when you guess his name correctly.
"Flavio hates you all."
The complete lack of respect the entire crew have for Flavio.
Pa-Patch: Hey, you want to know what smells really suspicious? Flavio's armpit!(This line comes complete with really small text and a fart sound effect) Smells like low tide!
Flavio: That's enough, you mutinous jokers!
The Cursed Chests, to the point during the third time around, Mario seems more annoyed than scared.
"I know she didn't turn into a pig just to feed her hungry kids!"
"Hey, this Twilighter is still a pig. .....Omigosh Mario, you can't tell her I said that!"
She is completely unable to tell the Punies apart, other than the main four. This results in some hilariously uninformative tattles if you ask her about them.
"Hm... I wonder how long Punies live. Smaller animals tend not to live as long as larger animals... ....maybe it's best not to think about it."
"You know what I wonder? Why are they called Punies? Because they're... Oh... right."
Tattle a Swooper for her opinion of its name.
Also, her tendency to point out the Fridge Logic behind some of the enemies, notably Bob-ombs and Hammer Bros.
When she first meets Dupree, she blows off his advances immediately. Unfortunately, he's a Recurring Extra, and her comments develop from simple disgust to outright despair if she keeps tattling him. And eventually all the way around to begrudging respect for how good he is at getting to each place in your journey before you.
"That's that totally gross guy, Dupree! What the heck is THAT guy doing here? Omigosh! You don't think he followed us here 'cause he's infatuated with me, do you? ...No? Oh, what, like it's not even possible?!? That's kinda insulting, Mario!"
"...it makes me want to yell, 'Hey stupid ocean! Look at me, I'm on vacation!!'"
"This guy's name is Fred. He's not very freaky for a Fred, though. What? Not all Freds are freaky? News to me."
The Tattle Log itself has a few amusing lines. On Kammy: "She's a nasty, magic-using crone, but you should still respect your elders! Remember that!"
"You wanna hate me, but you can't help but love the RAAAAAAAWWWWK!" Did Rawk Hawk write his own entry?
If you tattle Luigi the very first time you run imto him, Goombella's reaction will a slightly sarcastic "Who's this guy?", before pointing out that it's Luigi.
The crows in Twilight Town, when you hide in the shadows with Vivian.
Bowser can investigate his statues in his first level (which consists solely of walking to the other end of the room and being rude to a few underlings)... for the most part, he just comments about how handsome he is. But on the third one you get this lovely parody of the way Mario finds things, complete with Item Found music on the bolded statement:
Wow... what a profile! Although... this thing could use a good dusting... Huh? It looks like this eye is a little loose... Incredible! The statue's eye is a jewel! I got the Bowser Jewel! ...Just kidding.
One of the very first scenes in the game involves a massive horde of X-Nauts jumping Mario—and then Mario just walks away, as they're mindlessly pouncing on something (that is very much not Mario) in the middle of the crowd.
The scene shortly after the above where, in the middle of Toadsworth talking, 2 Pianta mobsters show up in the background and begin working two Craws (Gus and Garf) over before leaving. You're in Rogueport for 5 minutes and you've already witnessed a gang war.
During the final Bowser level, you can talk to that rich toad lady. Unlike the others, who cower in fear from Bowser, she begins admiring his horns before asking if she can mount them above her fireplace. Bowser's reaction is priceless.
Or "I am Bowser, businessman of legend! Fear my accounting!"
When you try to wake General White, the game snarks at you how that's not working. Each and every time. You do it about a dozen times. Twice. And each is funnier than the last. Stuff like "Sleeping like a 'stached baby." or "He woke up... just kidding, he's still asleep."
There's one point where the professor is giving his usual exposition, he stops saying 'no that's not' you current partner asks 'that's not what?' and Professor Frankley screams 'I DON'T KNOW' cue face fault from Mario and your partner looking like they have just received some damage.
The sidequest from the trouble center where you have to give a Goomba (who somehow got deep into Pirate's Grotto) a girlfriend. You're supposed to introduce him to Goombella, but you can introduce him to any of your partners. The funniest part is, Koops and Yoshi seem to be legitimately offended that he didn't want them. Also, Ms. Mowz will simply tell him that he shouldn't go into any dark alleys after that.
His reaction if you show Bobbery is hilarious too.
Goomba: I asked for a cute goomba gal, he's just some crusty old Bob-omb! Dude, what is WRONG with you?!
Bobbery: Well, you're not really my type either, you scaliwag!
After Chapter 7, there's a sidequest in the Trouble Center where you have to dress up like Luigi and meet someone who is a fan of Luigi. Hilarity ensues.
In case you're too lazy to click on the link above, the real Luigi shows up, the fan mistakes him for an imposter and chases him away.
During any battle, the audience may throw items at Mario's party to help out, but sometimes you will get a heckler that will throw rocks or garbage at you. You can actually counter the hecklers by making Mario or his ally run off the stage, go into the audience, and whack the heckler so they leave! Mario may be saving the world, but he won't hesitate to kick someone's ass for busting his chops during a fight.
The sheer fact that you can get X-Nauts in your audience cheering you on. Granted, they are the most likely to start throwing crap, but still.
"You never know when someone might go nuts and attack! Be careful! Live longer!"
"Nobody zings us like that! NOBODY!!"
During Chapter 3, in the Major-league locker room at the Glitz Pit, at one point Hamma Jamma the Hammer Bro. tells you that his father dropped out of Hammer School and went to Business school instead. Later on, Hamma Jamma says that his dad, the "Business Bro.", will be in the audience that day and that if things start going badly during the fight, could Mario knock the Business Bro. on his back so that he can't see what's happening!
Spike Joe (Another Major Leager) has a crazy obsession with his spike, and gets an equally weird one with Mario's mustache, trying to determine which is better, even suggesting a buddy cop show called "Mustache and Spike".
During TEC's Could-Say-It-But... quiz, one of the questions is "What does Grodus want to do with the 1000 year-old demon?", with two of the answers being "Cherish it always", and "Hang out with it".
Before disembarking at Rogueport, the tugboat captain tries to warn Mario that Rogueport is kind of a cesspool.
"What's that? You say there's a princess waiting for you? Er...right. If you say so."
Super Paper Mario
The dating sim parody between Peach and Francis the nerdy chameleon, which he uses to ask Peach to marry him. The possible responses range from accepting toconsidering; one is "How much money do you make?" Peach snaps at the player no matter which choice is picked.
And at one point Francis hovers the cursor over "Smooch" for a few seconds, then quickly picks something else.
Dimentio's Dimension D allegedly multiplies his power by 256, making him invincible... or at least it would, except it multiplies your power by 256 as well. When you beat him the first time, his reaction to this idea is subdued but priceless.
Fracktail, both before and after Dimentio fried his harddrive, had some funny lines. He even screams, "I AM ERROR!" at one point. Though, his system error meltdown and some of the emergency protocols his harddrive forces on him really say some stuff about his creators.
"Level 5 mustache detected!"
"SYSTEM MAY BE BUSY OR MELTING INTO SLAG."
"You lost everything. Way to go, genius."
"404 computer hamsters not found."
"THREAT LEVEL UPGRADED TO JELLY ROLL 1. DETONATION IMMINENT. BEEBLEBLIP!"
When he's searching his databanks for Mario's identification, his eye becomes the Wii Shop Channel loading screen, and he makes the same sound.
CTRL ALT DEL
Merlee and Mimi's catfight was surprisingly hilarious as well, including this wonderful line:
Oh, please, you make me gag. I am hot, no need to brag. And you...well, you’re a hag!
Bowser in the beginning cutscene.
Bowser: How many times do I have to tell those idiots? If you're the last one in, LOCK THE GATE!
"Hey, what's with the hairy guys up front! We SHAVE around here, minions!"
When the Cragnon chief is explaining that the Floro Sapiens have been making off with his people, he gives us this: "Now rescue team of Cragnons need to BE rescued!"
"Nerd Cragnons name them Floro Sapiens."
In reference to the sleeping at the top of the page, Merlumina is the only one to ever realize that Mario fell asleep.
Merlumina: And... You're sleeping again!?
Flint Cragley. Everything about him. CRAGLEY HO!
Also the fact that, of all things, you have to rescue his camera crew for him.
A Cragnon's reaction upon the heroes falling from the sky at the start of Chapter 5: "OH CRAG!"
The Catch Card description for the Dark Megabite: "This thing wants to end you. That's all."
A lot of Catch Cards, actually; Schlorp: "It's a vacuum cleaner! It's a worm! It's both! Don't feed it bombs, or you'll ruin its appetite. Forever."
"This Dark Ninjoe creeps around a certain secret pit. They move at the speed of DEADLY."
The last few lines of Tippi's tattle of the Cherbils: "Some say the gas comes from their mouths. Some say it comes from elsewhere... ...Oh, dear..."
A minor one but it shows a lot. After Mimi insults Peach for not being a fighter (stating that she has two 'boyfriends' to protect her), Peach stands her ground and tells Mario and Luigi to let her fight alone. After she screams if they understood, they don't object. They just stare each other say 'sure' and WALK BACKWARDS away from the Princess.
In Chapter 5, the Floro Sapiens capture some Cragnons and go down a pipe.
Tippi: "Disappeared through a pipe, did they?"
Bowser: "What am I, blind? Shut up."
Its interlude is golden. Nastasia punishes O'Chunks by forcing him to sing an song in Count Bleck's favor 1,000 TIMES! GOLD!
A lot of Luigi's lines are funny.
Luigi: Oh no! I don't give my name to scoundrels! Just watch as Luigi punishes you for your badness!
Luigi: The G-Great Luigi, you say? A... A daring defender? ...Me? Then I've got no choice! Luigi must spring into action! My fans need me!
No love for Fleep, the flipping Pixl?! To recap, he's been in the bathroom in Chapter 4 for 100 years, waiting for someone to bring him toilet paper. All the while, he sings nonsensical songs in a Spanish accent at the top of his lungs, punctuating each verse with "AMOOOOOOOOOOOORE!"
The other Pixls can be quite funny too, such as Boomer. To make sure that you and he are compatible, he asks you a series of questions, to each of which you have a choice of two answers...which are both always in the affirmative.
If you listen to Garson's story about the Ancients, he says that they spread word of the Pure Hearts and the legendary hero by building civilizations. If you're thinking that way, this can be summed up as them saving the universe by boning kingdoms into existence... Well, read the story he tells for context.
After defeating King Croacus, Tippi says quite possibly the most awesomely nonchalant line in the whole game.
"We have defeated your king. Get over it."
The Underchomp battle, which is one big Shout Out to the MOTHER series. The text in the battle in just ridiculous.
"[Character] dodges like a pro"
"Oh no! It's putrid!"
"Now that's hot!"
From when you beat Mr. L in his Brobot L-Type:
Mr. L: ""Awwww, WHAT?! No way! My Brobot L-type shoots missiles. MISSILES!
Tippi's snarky lines when you keep refusing to wear a space helmet.
So let me get this clear: you want to not breathe?
In Dyllis's kitchen: "Here, ve take flavor, und ve SPANK IT!"
Near the ending of the game, Peach mentions she, Bowser, Luigi fell through the floor. Bowser landed fine, she landed on Bowser and comments it was a surprisingly soft landing, then she proceeds to mention they found Luigi knocked out.
Tippi gushing over Luigi's jump in one of her hint tattles. For comparison, she's usually calm, if a bit sad.
Tippi: Luigi's jump is amazing! I'm sorry, Mario, but it's leaps and bounds ahead of yours!
When Squirps reveals the location of the pure heart;
Tippi: The Whoa Zone? You can't be serious. I demand answers.
Tippi: Who are you really you incontinent little imp?
Every. Flipping. Sammer Guy.
Whenever Bowser's Jaw Drops, it's pretty funny, but never moreso in the intro after Peach is compelled by Count Bleck into saying "yes" to marrying him, because it stays dropped. Then, the universe implodes.
What makes it even funnier is the fact that Dimentio actually references it later in the game:
Dimentio: You seem to be missing the ravishing princess and the arm-flailer.
Attempting to buy goods from Flimm with a full inventory gives us this gem:
Flimm: Here's a little business tip from a pro: try not to carry YOUR ENTIRE HOUSE.
The 66th Annual "That's My Merlee!" show. It implies that this same scenario has occurred sixty-six times.
Paper Mario: Sticker Star
In the opening cutscene, Bowser tries to steal the Sticker Comet. Three Toads try to stop him, only to send him flying into it once their grip gets loosened. When Bowser crashes into the comet, he's just sent flying with a little "plink" sound effect.
The Toad in charge of turning the "Things" into stickers actively trying to engage Mario into shady dealings...buying more things from the wall to the left.
The green Toad at the beginning of the game suggests you help "deburrito" Decalburg to return the town to normal. Once you actually do so, he gets rolled up in it. And you can just leave him there.
The Sombrero Shy Guys are just hilarious to watch. On the field, they're standing there, playing a catchy tune if you stand next to them. When you enter a battle with another different enemy, though, they rush over to the enclosing screen and join the fight to empower enemies after a turn passes.
And then there's the item that Sombrero Shy Guys sometimes drop: a sombrero. How does Mario use it? By flinging it at the enemy!
And if you fight the full Mariachi band of Sombrero Shy Guys in one level they'll play a little tune...and then throw their hats at you.
If you explore Yoshi Sphinx thoroughly, you'll fight Kamek, who will turn your entire sticker collection into sandals. Even with this making it a hindrance to fight, you can still beat him with them.
He does it again in your last battle with him. Kersti's attempt at a Badass Boast is just priceless.
Kersti: We'll beat him so bad he'll think his flips are flopped!
The dried out oasis has a Toad lamenting how it used to have water. Once you fill it with water, the scene changes to what it used to be with water and plants growing. Suddenly, the Toad that was mourning his bad luck comes down floating on the water wearing sunglasses and drinking juice, using a Totally Radical accent.
Many of the Thing animations are downright hilarious to look at:
Most people know about the Goat Thing by now, but the kicker is HOW you get it in the first place. Once you hit the tree, a swing descends far away between Mario and the Goat, and Birdo appears from the top and sings as he/she/it delivers the Goat to you. This is so a Squick moment.
The kicker is that Birdo is singing about its own ambiguous gender.
The line of Shy Guys. If you take the long way and get into the line, the Shy Guy before you is left speechless at what you're doing. If you cut in line, however, the Shy Guy will be annoyed instead.
Kamek being referred to as a hipster.
After fighting him in World 2-2, Kersti will comment "Hey, look at me, I ride a broomstick. I was into stickers before they were cool."
In each of the worlds, there's always a red Toad that needs help from being bullied by the native enemies. After saving him all the times, his house in Decalburg fills up with anecdotes of his travels. Once having read all of them, the Toad taking care of the house starts bawling in complete admiration and drops an HP-Up.
When you first run into the Boos, Kersti says "They look more "fun" than "terrifying" to me, but whatever", all while Mario is frozen in terror.
After collecting all of the Boos, Kamek casts a spell on the book containing them to create a giant Boo. As the music builds up and Mario and Kersti recoil in horror, the music stops and the scene suddenly freezes as Kamek casually walks past them. When he's gone, the music comes back and the scene continues where it left off.
In a world made of paper, the final boss is made of cardboard.
The museum texts showing Toads treating "Things" as it they were SCPs.
Kersti's snark about the door to a windmill being blocked by a windmill blade.
Kersti: What were they thinking? "Hey, guys, did we forget anything. Oh, yeah, THE FRONT DOOR ACCESS."