Gilgamesh begins what will become his long tradition of being the Trope Codifier for Braggart Boss. He is introduced dramatically leaping towards the bridge he will fight you on, letting out an Evil Laugh... but he misjudges the distance, hits the far side of the bridge (on his head, no less), and tumbles off the other side with a panicked yelp. Beat, he jumps back up on the bridge and poses dramatically. "Now we fight!"
The way the party's gazes all follow his course through the air is the cherry-on-top.
"Fly, Enkidu, Fly, my faithful companion...I SAID FLY!!"
"I.E, your weapons are as good as mine!"
And then there's what happens when you leave the area of your final battle with him...
Upon inspecting Gilgamesh's sword of Legend, Vaan (or whoever) points out that "It seems like an Ordinary Sword of Legend."
A Cockatrice from Giza Plains winding up in Jahara. What's really funny is that the Cockatrice itself knows how to talk (in a British Cockney accent, if you happen to have the Feather of the Flock key item) and it's having fun being there. Many Garifs are seen looking at it with a lot of interest. They all treat him like an honorary visitor to the village.
Balthier's Element of Treachery, "Here she comes!". Hilariously inappropriate considering he's just launched a meteor at the poor beast. The tone he says it in makes it even better!
Balthier's second quickening Tides of Fate, even though he's saying "Heads Up!" it really does sound like, "Surf's Up!"
Basch didn't betray his country, it was his evil twin. He's telling the truth, but when said like that it sounds too silly to be true.
Vaan asking Fran her age (seemingly a fair enough question, as Fran is the only viera of the party and ages differently from humes), and everyone's reactions to him afterward.
Fran: *silence, then turns away, offended* Balthier: Nice, Vaan. Ashe: Ugh. Larsa: Surprisingly rude. Penelo: Try to grow up, please?
Balthier's disgust for Jules when the party is trying to get into Draklor Laboratory.
Vaan: So...you two were close huh? Balthier: Close enough for fisticuffs. Driver! Faster, if you please. I would be loathe to expend any of the violence of my present mood on my companions.
The Mandragora's pre-battle cutscene in Sochen Cave Palace, complete with goofy cartoon sound effects.
That entire battle was absolutely hilarious (if not annoying, or outright deadly if it drags on for too long) because they ran around the arena in order to avoid your attacks. If one can imagine it, picture all three of your allies running around the room trying to bash their heads in as if it were a Benny Hill chase scene, it's hilarious. The death scene is the icing on the cake, upon which they ascend to the great beyond, with the pumpkin star losing his head and him trying desperately to get it back on as both it and the monster ascend to the pearly gates.
Also funny is the petition you are given for it from the Archadian Wayfarer, who states that the clans refused his "expertly written bill," which looks like a bunch of scribbles. Also, when you talk to him again, you can have the bill presented again, followed by the normal message from the game asking if you which to confirm the location of the petitioner. If you agree to this...
Archadian Wayfarer: Are you as witless as you are craven? I'm the petitioner! Me! East to the Highlands, north into the Fields of Eternity, and into the caves! Got it? You're quite sure? Shall I repeat it again!?
At some point in the game, Gabranth and Vayne are talking. After they finish, Vayne dismisses Gabranth for Cid. Cid enters the room talking to Venat, but he looks as if he's carrying on a conversation with himself. Gabranth sees this as he's leaving the room, and makes a motion as if he's completely dumbfounded by what he just saw.
While the scene itself was quite serious, Basch getting bitch slapped by Ashe on the Leviathan was worth a chuckle or two.
At one point (specifically the cutscene right before the battle with Vossler), Fran goes against her calm self and flips out, breaking her cuffs and taking down every guard around her.
Penelo: What's wrong with her?
Balthier: I always knew Fran didn't take well to being tied up. *guard lands near them* I just never knew how much.
In Old Archades, the player can encounter a troupe of eight dancing moogles. Talking to a seeq nearby reveals that he is their owner and plans to sell them. The player can alert the moogles to this. Talking to the seeq again has him regale how the moogles beat him within an inch of his life.
Seeq: I'll never look at a pom-pom the same way again.
At the Sun-Cryst, after Ashe delivers a Shut Up, Hannibal! to Cid, he teleports to the center of the room to look at the Sun-Cryst, and her expression is exactly the "wait, huh?" reaction you'd expect.
Cid himself steals the show both times he confronts your party. The guy is enjoying himself way too much, and atop the Sun-Cryst especially it's jarring to see his Laughably EvilLarge Ham contrasted against the party's seriousness.
Ashe: I will not suffer you to have it, the Sun-Cryst be damned! Cid:Oh-ho, be sure that it is! For what other reason do you think you've brought us here!?
Admit you broke down into laughter near the beginning of the game, when Vaan takes a pouch of gil from the Imperial guard. His Large Ham "THE BOY!!!" certainly helps, as well as his reaction when Vaan manages to escape in the crowd.
Afterwards, Penelo takes the pouch because it's supposed to be for "the people of Dalmasca."
Vaan: Yeah, but I never said anything about taking it back from me!
You go and fight the Wraith under the impression that it's the woman's child who has locked himself up, out of fear, inside the abandoned house. You defeat the Wraith and report back to the woman... and suddenly a little Seeq comes walking out. Turns out it wasn't her child after all.
The above instance isn't the only time you screw things up inadvertently. Late in the game, you're able to hunt the Wild Malboro, described by Rena (the bill poster) as the enemy of all Viera, kept in check by the Rafflesia...that you just vanquished a while ago.
Escaping the Leviathan. Vossler comes in and announces that they've secured an Atomos with which they can escape. Thing is, the Atomos is a small transport ship, and a rather unelegant one at that. Hardly fit for a leading man, as Balthier takes his time to lament. Vaan sees his chance and asks if he can fly it then. Fran doesn't think so.
Vossler: We've secured an Atomos, come! Balthier: An Atomos? All skiff, no ship... hardly fit for a leading man. Vaan: So I can fly it? Fran: Are you mad?!
When you meet Al-Cid for the first time at Mt. Bur-Omisace, Larsa approaches him and extends an arm for a handshake. Cid instead reaches down and ruffles his hair, and Larsa gives a little glare and knocks his arm aside.
Shortly following this, Al-Cid makes a pass at Ashe, commenting "So it is true what they say. Stunning is Dalmasca's desert bloom." Larsa looks and sounds utterly disgusted.
In a couple of cutscenes you can hear Vaan and Penelo joking around in the background of serious conversations Ashe is sharing with other party members.
Vaan: *after finding the exit from Ozmone Plains to the Golmore Jungle* I guess this one is a success. Penelo: Wow. I'm impressed, Vaan. Vaan:I got a good feeling! Larsa: This is the way! (...) Vaan: ... Right? Penelo: Don't encourage [Vaan]. Vaan: I'm not that bad, am I? Penelo: "I got a good feeling!" Larsa: *chuckles* Vaan: Larsa, please, this is serious. Larsa: Oh, oh... I-I'm sorry. Penelo: Don't be, Larsa. Somebody's gotta put him in his place.
At Phon Coast, when Balthier is discussing his past with Ashe:
Vaan: Hey! *points across the water* See that? Come over here. Penelo: *moves closer to see where he's pointing* Vaan: *attempts to shove her into the water* Penelo: Hey! Watch it! *punches him in the arm* Like I said, it's a beautiful view... except for you. Vaan:Thank you.
During Larsa's introduction as 'Lamont', Balthier and Basch appears to be suspicious of his presence in Bhujerba, while Vaan seems to have taken an immediately liking to him and reassures that 'Lamont' will be in good hands during the visit to the mines. Balthier and Basch's exasperation at Vaan's eagerness to help a random stranger at face value is quite amusing to see.
What really sells the above is that despite being explained to that Basch is not to be revealed publicly, Vaan assures Lamont that Basch and him will keep them safe.
Balthier isn't so happy with Ashe's explanation of the treasure of the Tomb of Raithwall...
Ashe: In this Esper we now command rests a power whose worth is beyond any measure.
Balthier: Is that so? Call me old-fashioned, but I was hoping for a treasure whose worth we could measure.
The Running Gag of various characters, even members of your own party, referring to the Dalmascan Resistance against the Archadian Empire as the "Insurgence."
Balthier: So, we keep to our affairs, and she to hers. I doubt we'll find her wanting in valor... Being such an upstanding member of the insurgence.
The party reaches Archades and it's not what Vaan was expecting, in fact, it smells more like a sewer. Balthier explains that this is where the runoff from the city proper stays because "even Empires have need of sewers." The city itself is impressive, though it "reeks of a different kind of filth."
Balthier: Let's be off. We can follow our noses to Draklor.
Getting Bhujerban NPCs drunk on Madhu in exchange for gil.
"I said you're the one that stinks, hamshanks. Hear me now?"
The party manages to trick Halim Ondore into thinking they already have Larsa on their side with Vaan's impression of him. Somehow, it works, but...