The part where Cloud was dressed up as a Shinra soldier for Rufus' welcoming parade, and the parade's leader asks what they should finish the sequence with. Because of Cloud's previous parade failure, he asks Cloud to tell them what to do. Cloud stands tall and spins his Shinra-issued gun — with the music of the victory fan-fare, just like he does when you win a battle. Everybody's like, "WOW!!" and "That's awesome!"
From that point on in the game, you'll occasionally see Shinra soldiers practicing the finisher...with the victory fanfare playing every time!
"You're the slum drunk".
In Junon, the party discusses how to get up to the upper level, and it's mentioned that the only way to do so is scale a tower with a high voltage electricity risk. Their unanimous response? "Cloud should be OK then." "Yeah, good luck, Cloud!" "We're all counting on you, Cloud!" And then they all walk away, leaving Cloud stammering, "W-wait a minute!"
And when he finally reaches the boat after having to go through all sorts of silliness to keep his disguise as a Shinra soldier up, he can potentially find out from Red XIII that his companions realized there was an easier way in by just riding the dolphin to the dock.
Sit your ass down in that chair anddrink your goddamn TEA!
One of the funniest moments in this game was when Cloud decided to dress up as a girl to seduce Don Corneo; he'll never live it down.
The whole scenario with Don Corneo is hilarious, from Aerith simply mentioning Cloud should crossdress, to an actually creepy moment where Cloud blacks out at the Honey Bee Inn only for the scene to have a Mood Whiplash when he wakes up and find a suspicious man not wearing much slapping him around, to the fact that you can rig it so Corneo chooses Cloud as his pretty girl.
Not simply mentioning Cloud should crossdress, but then mocking him and calling him "Miss Cloud" for going along with her plan. Seriously, Aerith's personality during the whole Midgar plot arc is pretty shocking if all you know about her is her FlanderizedMysterious Waif, Too Good for This Sinful Earth persona from the spinoffs.
Also, when Aerith contributes to the threatening of Don Corneo's testicles ("I'll rip them off!").
The whole scene of interrogating Don Corneo is both hilarious and awesome.
If you dress up Cloud in the worst possible get-up, he's resigned to spending the night with a couple of Don Corneo's goons in a small, messy room. Said goons make sexual advances towards Cloud, which, using the game's low-polygon character models, consists of them slowly lurching towards Cloud like zombies.
Especially when Tifa and Aerith catch Cloud almost kissing the old perv. The dialogue before that is particularly funny:
Don Corneo: Is there someone else?
Cloud: Yeah, there's this guy named Barret...
Speaking of Barret, "VERMIN? Y'all Shinra're the VERMIN, killing the planet! And that makes you King VERMIN! So shu'up, jackass!"
And another line from Barret when you're leaving Midgar for the first time is an optional classic. If you choose to take Tifa and Aerith as your party members, he'll give you an annoyed "Figured you'd do something like that."
On the other hand, if you choose to take Barret and Red XIII with you rather than the girls, they describe this choice as "Very..." "...interesting" (finishing each other's sentence when doing so), then saying "OK, have fun..." "...Boys!"
Who could forget those classic NPCs in one of the many bars: "It sounds like there's something going on outside, but I'm too drunk to care."
Early in the game where Cloud and the others infiltrate the Shinra HQ, you can choose whether to fight your way through the main entrance, or sneak up the staircase in the back. If you choose to take the stairs, you hear Barret constantly complaining about the huge trek up the stairs, which causes Tifa to snap:
Tifa: Would you stop acting like a retard and CLIMB?!
Late in the game when Cloud disappears from the party, after Tifa escapes the gas chamber and runs out to the cannon in Junon, Scarlet catches up to her and starts to slap her. You are then instructed to press O to slap Scarlet back. Having to participate in a bitch slapping contest between two women is just plain hilarious.
In the beginning, you can choose whether or not to order a drink from Tifa. The choice to get one is "give me something hard." That's not innuendo at all.
Later, when Tifa asks how you slept, you can remark on how you slept well because it was next to her. If you choose this, her response is an amusing "I don't know what you mean."
Most of Cloud's jokes can be extra effective for those who, say, saw Advent Children and Kingdom Hearts first and were exposed to his Flanderized angsty attitude. An especially funny one, if simple one, comes when Cloud gives Yuffie advice on how to combat motion sickness, where he mentions that back when he was in SOLDIER they had to ride in trucks all the time and that "It sucked." Considering the events that immediately preceded this conversation, you wouldn't expect our hero to be in the mood for such a silly line, which makes it even funnier when it comes out of no where like that.
"All right, everyone. Let's mosey."
Also, most of the stuff that comes from Yuffie's mouth.
[Shinra troops ambush the gang] "I didn't plan this one!"
[Cloud debates what to do with a piece of Huge Materia] "Can I have it?"
[In response to Vincent's lament about Lucrecia] "Yawn, boring story #1."
Heck, right before the final showdown she opts to not get in the fight, but proceeds to freak out and claim that the Materia is "all hers".
Not a Yuffie line, but if you get her to go on the date with Cloud, she awkwardly kisses him, to which he doesn't respond, causing these lines:
Yuffie: Say something!
[A slapping sound is heard]
Her exchange with her father at the top of the Pagoda - just after a very emotional conversation about the state of the nation and her father's failing, he lets everyone else go out and then starts asking Yuffie if the party will be wanting all their Materia after the last battle. His last words to her are something like, "Come back! With the Materia!" Like daughter, like father, eh?
The fight with Palmer. At the end, a truck steals your kill (sort of...he doesn't actually die).
Plus he does the stupidest little dance during the battle, and occasionally taunts you by spanking his butt.
His first appearance in the game. "Rate Hike! Rate Hike! Tra la la!"
This isn't what you would consider to be a hard battle or anything. Not like the Materia Keeper or Gi Nattack, where you actually had to, you know, try. Fighting with Palmer is more like a personal challenge to see how long it takes to make the battlefield explode into a mess of butter and shrapnel. Palmer stands on one side of the screen, wiggling his fat body about in a presumed attempt to move, or perhaps communicate. Occasionally, he pulls out a gun and fires it at you. But since he went and ate all the bullets, thinking them to be Pez, the thing is running on a combination of materia and AAA batteries, and instead mimics the effects of Bolt 2, Fire 2 and Ice 2. But, he is susceptible to the effects of Stop, meaning that if you've got Seal Evil or some other equivalent on hand, he won't even be able to get an attack off. If you don't paralyze him, it's no big deal, but be warned that Palmer will periodically lean over and slap his ass in an attempt to be provocative, but ends up disgusting you more than anything. Kick his ass to high hell, unloading everything you've got onto the chubby guy. The only thing that will not affect him is gravity-based attacks, quite possibly because a body as large as his tends to produce a gravitational force far stronger than anything you could ever conjure up. Anyways, once you've hurt Palmer badly enough, the Tiny Bronco begins to move. Palmer will turn tail and hobble his fat ass along, trying to catch the vehicle that he is attempting to steal. At this point, the game rewards your patience by hitting Palmer with a truck. To add insult to said injury, your team steals his armor (the Edincoat) before leaving him to bleed rich and creamily.
Aerith's mistranslated line: "This guy are sick."
Red XIII's scene in Costa del Sol, you find him calmly playing with some kids and their soccer ball, if you feel like being particularly cruel, you can kick the ball... right into his face, his response is to jump up and bark at you. If you talk to him after that, he just growls at you.
Meanwhile, Hojo is chilling out on the beach surrounded by groupies. And "getting a tan" as he puts it... while still wearing his labcoat.
At the Golden Saucer, you choose to have someone ride the gondola with you. While most of the characters are amazed by the sights and sounds. If you chose Cid, he just sleeps through the entire ride.
How about Red XIII in a stolen Shinra uniform (with his tail still sticking out), dancing around like a complete moron as he tries to keep his balance on two feet?
The best part is that he's standing frontways, and it's only when you talk to him and he says "I think I pass for a human being perfectly well" that he immediately turns around and you first see the tail sticking out.
Near Gongaga, you come across Reno and Rude of the Turks. Prior to this, they've been intimidating and Badass... but here, while they aren't noticing your presence at first, they're gossiping like teenage girls about who has a crush on whom (Rude likes Tifa, not Elena, who likes Tseng, even though Tseng likes Aerith....) It gets funnier when Elena walks up beside you and comments on how stupid they're being and insisting that she and Tseng's relationship isn't like that... only then to realize who it is she's talking to and alerts Reno and Rude to your presence.
Another funny Elena moment is later in Icicle Inn, where she confronts you about Tseng getting nearly killed back in the Temple of the Ancients, and she attempts to punch you. The outcome is funny either way: if you dodge, then she swings, misses, falls, and goes rolling out of Icicle Inn. If she decks you, then you fall unconscious... and Elena promptly freaks out and feels guilty about this.
The Turks again. Reno, Rude, and Elena are on vacation in Wutai, and refuse to fight you as long as they're off duty. When Shinra troops try to get them to help track down Don Corneo, Reno turns the mission down and snaps, "Go away! Just looking at you is making me sober!"
The play you're coerced to star in during the date scene, especially if you don't do what you're told (e.g. kiss the Evil Dragon King).
If you mess up lines in the play... FLYING KICK!!!
When Cloud is under Sephiroth's control and about to attack Aerith, the two other characters with you yell out "Cloud!" Except for Cid, who yells out "Dumbass!"
Barret in sailor uniform.
Cloud: You look like a bear wearing a marshmallow.
This counts as a possible mood killer considering what happens, but in the PC version of the game, if you take Vincent in with you in the Forgotten City, his model begins spazzing out when you go down to confront Aerith, standing with his leg outstretched and his cloak hanging above him. After Aerith's death, it just gets worse as he walks towards you with one leg pointing towards the sky, his leg outstretched again when he walks in front of Cloud, making him look like he's kicking Cloud in the crotch.
Of all people, Sephiroth gets one when you meet him in Shinra Manor. After going on and on with his monologue, he beans Cloud over the head with a materia like it was a friggin' baseball, then flies out like Superman. And this is all with the Super-Deformed world-map graphics.
Earlier in the same place, during Sephiroth's breakdown in Cloud's flashback, he says "I'm going to see my mother" and skips out of the room. He then proceeds to slaughter the entire town in about 15 seconds, which, while horrible, is pretty goofy when you think about it.
Giving Red XIII the name "Nanaki", when you first encounter him, which makes it hilarious when the party visits Cosmo Canyon later in the game and is surprised that his real name is Nanaki.
Naming every playable character Sephiroth (the story will make hilariously little sense). Alternatively, in the PC version, modding it so all the playable characters' models are that of Sephiroth.
This troper gave most of his characters silly names (for example, Cloud was called Penis), but one of the best ones had to be Cid. Since everyone in town was referring to him as Captain, that's what this troper named him...leading to the line, "My name is Captain, but everyone calls me 'Captain'".
If you do really, really bad in the parade...
Unseen Shinra Exec: That was terrible! Send that soldier a bomb!