Gilgamesh continues his tradition of hilariousness in his appearance as a Bonus Boss. He is introduced dramatically leaping from his lofty perch to the bridge you fight on, laughing all the way... and misjudging the distance, going too far, and hitting his head on the side of the bridge as he tumbles clear off the thing. And then he just jumps back up and declares "Now we fight!"
"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, 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) 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.
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 regail 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.
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.
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?!