The "Lady Smith" splicer's funny rants. "You're worthless, you're nothing!" "There's proper folk, here. You don't fit in!" Check out her quotes.
Lady Smith: You call that tenderloin? If you serve that in any respectable hotel in New York, they'd laugh you out of town! Lady Smith: CHARLES? I think the Negro cook's been stealing!
While many of the Splicer rants across both games are great examples, this example from Doctor Grossman has got to be one of the best:
Dr. Grossman: I made a promise to do no harm... and I mostly meant it.
When you first get the Electro-Bolt plasmid in the first game, it's a very scary scene. However, the mood is lightened when Atlas says "Steady now! Your genetic code is being rewritten! Just hold on, and everything will be fine!" Dark humor on the level of Portal, but also creepy in how normal that kind of thing is to Rapture citizens.
When you use the Enrage plasmid to make enemies fight each other, it's always a gas, especially when they're angrily cursing each other out. Also funny if you use it to make a lone splicer lash out at a Big Daddy.
Suchong: Get AWAY, you filthy little shit! [smacks the Little Sister] [The Little Sister cries] [Big Daddy growls] Suchong:NO! NO! GET AWAY! AGH!
In Fort Frolic, you fight out a boss battle against many, many Spider Splicers... to the tune of Waltz of the Flowers.
If you steal the candy bar next to a Little Sister in Tenenbaum's safe house, this is her response:
Little Sister: That's mine!
The Breadwinner Splicer: "GET OUT OF MY FUCKIN' OFFICE!!!"
Dr. Steinman - a plastic surgeon with a very...interesting definition of beauty - is freaky as all get out, but he has some of the best lines — "STOP CROWDING ME! LOOK IN A MIRROR! LOOK IN A MIRROR!"
When you enter his office to fight him:
Dr. Steinman: An intruder! He's ugly! UGLY! UGLLLLLLLLLLLLLLY!!![Begins firing Tommy gun.]
Even better is the recording you get after his death, "Not What She Wanted". It points out the explicit moment that he fully went off the deep end.
Steinman: I never realized how much her face... sags. Scalpel.
Atlas's Irish accent can either be charming or flat out hilarious.
"Goddam SPLOICERS!!!"
Atlas' outburst when Ryan kills Julie with poisonous gas is rather darkly humorous.
Atlas: Every toime we get a yahd ahead, Roian goes and moves the goal posts down to the other end of the field!
And, of course, "Fistful O' Loitnin'" when you get the Electro-Bolt plasmid.
Atlas's over-the-top Irish accent only gets more ridiculous when Frank shows off his true identity, and mocks you by getting REALLY ridiculous with it.
"Really woun'ja up with that wife and child bit.[ridiculous, Lucky-Charms-like brogue] Ohhhhhhhh, me pohr Moira! Ei me weeee baybee Pahtrikk...."
When you're going after Hector Rodriguez for Cohen (the Nitro Splicer who continuously runs from you), make use of the Hypnotize Big Daddy plasmid and watch the thing go thundering down the hallways after him. It'll be a hilarious chase that will go halfway across Fort Frolic before Rodriguez finally gets beaten down.
When Fontaine realizes that "would you kindly" isn't effective at controlling you anymore, after asking you in vain two or three times to "Go get stepped on by a Big Daddy, would you kindly?" Something about the increasingly confused and irritated tone of his voice was just hilarious. It then stopped being funny and became really unpleasant when he reveals he knows another code phrase. One that gradually stops your heart.
Julie Langford's vocal impressions of people in her audio diaries are quite hilarious. Listen to her deep-voiced impression of Andrew Ryan, and the classic "Harness the flame, harness the mist!", and try not to laugh. It's not easy.
Julie Langford is voiced by the same woman who voices the "Lady Smith" Splicers. The woman is a master of having every word out of her mouth sound like it has air quotes around it.
It rarely happens and it's hard to catch, but when you alarm a Big Daddy that is currently escorting a Little Sister, he'll hoist her over his shoulder, and in the process, the Little Sister will yell out a joyous "WEEEE!" as she's flung over in the most adorable manner.
The game has numerous large, open-ended levels, each filled with a great deal of missions, but even more filled with hidden passages, ammo reserves, and security bots to reprogram. There's a lot to play with, and you're almost guaranteed to find your own humorous way to mess with the prowling Splicers.
One fun trick when being engaged by Splicers is standing behind a Big Daddy, at which point the Splicers will then try to shoot youthroughthe Big Daddy. Sit back and watch the carnage.
The "Cheap Son of a Bitch" audio diary by Suchong. "Go suck egg" is basically Suchong's hilarious version of "Go fuck yourself." Not to mention "egg" means testicle in both Spanish and Chinese slang.
Despite being a really nasty Mad Scientist, Suchong's audio diaries typically have a twist on them that makes them darkly comedic. This includes his own, extremely satisfying demise.
Suchong:[On the Telekinesis Plasmid] Cannot stop speeding bullet, but can catch and throw fast moving object. Problem not with Plasmid. Problem with reaction time. [Beat] Suchong just get new idea for Plasmid.
Anya Andersdotter may have a tragic backstory that includes the loss of her young daughter and her resultant decision to become a saboteur/assassin, but even though she only leaves two audio diaries behind it's evident she was a Deadpan Snarker right to the end:
Anya: Piece of cake for an electrical engineer. Too bad I design ladies' shoes.
Upon equipping the Big Daddy Bodysuit:
The Big Daddy bodysuit gives you a 25% resistance to all damage!
.Lady Smith: You call that tenderloin? If you serve that in any respectable hotel in New York, they'd laugh you out of town!