fallout 3... when you ask jericho to wait here then right away talk to him again
"what the [censored] man ive been standing here forever?"

"I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely."
- James, FO3.

"Obstruction detected, composition: titanium alloy supplemented by photonic resonance barrier. Probability of mission hindrance: zero percent!"
- Liberty Prime, FO3.

"You purchased my contract from Ahzrukhal? So, I am no longer in his service. That is good to know. Please, wait here. I must take care of something."
- Charon, FO3.

"Thanks for taking a chance on a naive young girl from California with stars in her eyes and a pneumatic gauntlet on her hand."
- Veronica, FO: NV.

"Nope. Well, not now. It takes a few years after bein' dipped to get the juices flowing again. Why?"
- Marcus, FO2.

"I'm the one who put the 'death' in the deathclaw!"
- Goris, FO2.

Seconded.

http://www.youtube.com/watch?v=KICszQNDUOA

Fantastic is hilarious. There was another line also, from memory: it's not that I don't know what I'm doing, I just don't know the effects.

Also good examples of how the writing is better in NV than in F3, even if I love F3 too.

For sheer comedy value/Bethesda dialogue at its finest; "I heard you blew up Megaton, i'm very dissapointed in you"

I loved all the floating combat dialogue in the originals; "im gonna beat you like a red-headed stepchild" springs to mind.

"You again? You should meet my bookie, you have something in common - everytime I talk to you I lose caps!" - Billy Knight

"A toaster is just a death ray with a smaller power supply!" - Toaster from Old World Blues

"Hey local, shouldn't you be banging rocks together or something?" - Brotherhood Outcast

"I'm about as irradiated as I can get without burning a hole through the floor." - The Lone Wanderer

"Too... Tired... To be.... Snide..." - The Lone Wanderer

"OM NOM NOM!" - Dog/God

"ICE CREAM!" - The Courier

"I IS SCIENTIST." - The Courier

"What are Flowers of Pock-Lips?" The Courier

"Most people have evil spirits. You? You have stupid spirits. Go see shaman, get hole in head... Big hole... Very big... Huge." - Sulik

"I don't care if you were dropped on your head as a kid. No guns in the city limits." - NCR Gate Guard

"Well, says No-bark, we got a chupacabra with an automatic weapon. And that's when they get real quiet, 'cause now they see the predicament we're in." - No-Bark Noonan

"TAKE DRUGS, KILL A BEAR!" - White Bird

"He's not dead... it's a trick. Get an axe!" - Dean Domino

"Witch! Witch! You should be burned for all the people you've turned into newts!" - Freeside Residents

"Exterminate!" - Freeside Securitrons guarding the North Strip Gate

"I once tried to measure my Charisma on a Vit-o-Matic Vigor Tester once. The machine burst into flames." - Mr. New Vegas

"Position Bravo Bravo Charlie, the Doctor is coming!" - NCR Emergency Radio during Hoover Dam

"Do you know how many coffee cups giant robot brains in jars use on a daily basis? Not [censored] many!" - Muggy

"Well, maybe next time you hear me telling you it's a bad idea to charge a Nightkin with a Penknife, you'll listen." - Courier's Brain

"Who's the flatware [censored] now O!? - Muggy

"I hate myself for asking you this but..... did you bring me any new mugs? UGHHHHHHHHHHHHH..." - Muggy

"You some kind of sick mug hoarder?" - Muggy

Among others.

I still crack up when I read the majority of those. One of the reasons I love this series.

"Nice robot" - Great Kahn in the Great Kahns' Armory

The way he says it always makes me laugh, reguardless of how [censored] my day has been

"My story? Tell you what, kid. My story's a lot like a Deathclaw's tongue. It's long, messy, and you don't want to get too personal with it. Understand?" - Desmond Lockheart

Friggin' funny ghoul.

The Wasteland Survival Guide quests have some of Fallout 3's greatest quotes:
"Oh, disarming it's real easy. Just jump up and down on it. You go first."
"It repelled their limbs from their body. Can you make one that works on people?"
"On a scale of one to ten, I'd say it's a "shut the **** up and fix me."

"I'm going to have you killed now....Relax, I'm ****ing with you." - Caesar

"Hey, I'm one of you! Don't eat me, eat the smoothskin! Oh, uh, sorry boss." - Raul when entering the REPCONN Test Site

[What do you do here?] "****, man, everything. I push buttons, I turn dials, I read numbers. Sometimes I make up little stories in my head about what the numbers mean." - Fantastic

"Jumpin Jesus on a pogo-stick! I can't belive you made it out alive..."
- George from Fallout New Vegas