GLaDOS goes out of her way to foster quite a bit of appealingly darkParanoia Fuel in the introductory chambers, such as her elaboration of the Emancipation Grills, "which may, in semi-rare cases, emancipate dental fillings, crowns, tooth enamel, and teeth."
"These intra-dimensional gates have proven to be completely safe. The Device, however, has not. Do not touch the operational end of The Device. Do not look directly at the operational end of The Device. Do not submerge The Device in liquid, even partially. Most importantly, under no circumstances should you- *Static, slows to a stop.*
"As part of a previously mentioned required test protocol, we can no longer lie to you. When the testing is over, you will be... missed!"
Appropriately, one of the lines that best establishes and encapsulates GLaDOS's character is also one of her funniest:
Please note that we have added a consequence for failure. Any contact with the chamber floor will result in an unsatisfactory mark on your official testing record, followed by death. Good luck!
GLaDOS's insults early on in the game are made funnier still by the time and effort it usually requires for the player to realize they've been insulted at all. A good example is her backhanded, importance-deflating praise toward "[subject name here]."
GLaDOS's feeble efforts to deter the player from advancing toward her chamber, and her growing resignation toward their upcoming face-off.
You should have gone left before. It's funny, actually, when you think about it. Someday we'll remember this and laugh. And laugh. And laugh. Hoooooohboy.
Didn't we have some fun, though? Remember when the platform was sliding into the fire pit and I said "Goodbye!" and you were like "No way!" and then I was all "We pretended we were going to murder you?" That was great...
Though it can't be said for certain why following line was Dummied Out, it clearly wasn't because it's not funny:
And the final battle with GLaDOS, particularly before you incinerate her Morality Core:
"Deploying surprise in five, four — *clunk* — time out for a second. That wasn't supposed to happen. Do you see that thing that fell out of me? What is that? It's not the surprise; I've never seen it before. Nevermind. It's a mystery I'll solve later... by myself. Because you'll be dead." "Maybe you should marry that thing since you love it so much. Do you want to marry it? WELL I WON'T LET YOU! How does that feel?" "That thing is probably some kind of raw sewage container. Go ahead and rub your face all over it." "I'll tell you what that thing isn't: It isn't yours. So leave it alone." "Have I lied to you? I mean, in this room? Trust me, leave that thing alone." "You are kidding me. Did you just stuff that Aperture Science Thing-We-Don't-Know-What-It-Does into an Aperture Science Emergency Intelligence Incinerator? That has got to be the dumbest thing that — whoa, whoa, whoaaa, WHOAAAAA..." "That thing you burned up isn't important to me. It's the fluid catalytic cracking unit. It made shoes for orphans. Nice Job Breaking It, Hero."
And after the core was burned wasn't too bad, either.
"Don't believe me? Here, I'll put you on. Hellooo!THAT'S YOU! That's how dumb you sound!" [warping groan] "You think you're doing some damage? Two plus two is…" [pulsing static] "… ten. IN BASE FOUR. I'm fine!"
The Curiosity Core. "What's that? What is that?Ooo, that thing has numbers on it! Ewww, what's wrong with your legs? Is that a gun? Where are you taking me? Oh hey, you're the lady from the test! Hi! Do you smell something burning?" Yes, little core, I do.
Even then, the dry redundancy with which she describes the circumstances behind the Morality Core's installation, amplified further by her flat, robotic delivery, lends that moment a good bit of comedy regardless of how chilling it otherwise is.
"There was even going to be a party for you. A big party. That all your friends were invited to. I invited your best friend the Companion Cube. Of course, he couldn't come because you murdered him. All your other friends couldn't come either because you don't have any other friends, because of how unlikable you are. It says so right here in your personnel file. "Unlikable. Liked by no one. A bitter, unlikable loner, whose passing shall not be mourned." Shall not be mourned. That's exactly what it says. Very formal. Very official. It also says you were adopted, so that's funny too."