Thank you, ladybug!! 
Something Blue is another great episode for favorite exchanges. My favorite of the episode (and one of the few Riley bits that I liked) was outside the wedding boutique. I’m not going to reproduce the whole scene here, but suffice it to say that it was hilarious, especially this part:
Who can forget blind Giles reacting to Buffy and Spike’s passionate kissing?
“Stop that, I can still hear you smacking!”
Phases–Willow to Oz upon finding out he’s a werewolf:
Willow: “Well, I like you. You’re nice, and you’re funny, and you don’t smoke. Yeah, okay, werewolf, but that’s not all the time. I mean, three days out of the month I’m not much fun to be around either.”
Bad Girls
Wesley: “Remember the three key words for any slayer: preparation, preparation, preparation.”
**Buffy: **“That’s one word three times.”
Choices
Buffy* (about Oxford)*: “That’s where they make Gileses.”
Amends
Buffy: “What are you doing for Christmas?”
Willow: “Being Jewish. Remember people? Not everybody worships Santa.”
Later in the episode:
Xander: “That’s the Christmas spirit.”
Willow: “Hello? Still Jewish. Hanukkah spirit, I believe that was.”
Willow* (to Oz)*: “Well, you know, we’re alone. We’re both mature younger people. And so… we could… I’m ready to… with you. We can do that thing.” <—The line itself might not be so great…but it’s the way she says it that is so utterly adorable…
The Prom
Anya: You know, you can laugh, but I have witnessed a millennium of treachery and oppression from the males of the species. And I have nothing but contempt for the whole libidinous lot of them.
Xander: Then why are you talking to me?
Anya: I don’t have a date for the prom.
Xander: Well, gosh. I wonder why not? It couldn’t have anything to do with your sales pitch.
Anya: Men are evil. Will you go with me?
Xander: One of us is very confused, and I honestly don’t know which.
Buffy: I’m gonna give you all a nice, fun, normal evening if I have to kill every person on the face of the Earth to do it.
Xander: Yay?
Anya: Look, I know you find me attractive. I’ve seen you looking at my breasts.
Xander: Nothing personal, but when a guy does that, it just means his eyes are open.
Quotes courtesy of Laugh Lines, Love Lines
The Freshman
Xander, in front of Kathy, who does not know Buffy is the Slayer.
“Some friends of Buffy’s played a funny joke. They took her stuff,and now she wants us to help get it back from her friends who sleep all day and have no tans.”
I’ve got too many…
Willow: No, it’s fine. I’m ‘Old Reliable’.
Xander: She just means, you know, the geyser. You’re like a geyser of fun that goes off at regular intervals.
Willow: That’s Old Faithful.
Xander: Isn’t that the dog that, that the guy had to shoot…
Willow: That’s Old Yeller.
Buffy: Xander, I beg you not to help me.
Willow: Say, you all didn’t happen to do a bunch of drugs, did ya?
Willow: Oh, right. Me and Oz play ‘Mistress of Pain’ every night.
Xander: Did anyone else just go to a scary visual place?
Buffy: Oh, yeah.
Xander: Dammit! You know what? I’m sick of this crap. I’m sick of being the guy who eats insects and gets the funny syphilis. As of this moment, it’s over. I’m finished being everybody’s butt monkey!
Buffy: Check. No more butt monkey.
Willow:I’m good at medical stuff, since Xander and I used to play doctor all the time.
Xander:No, she’s being literal. She used to have all these medical volumes, and diagnosed me with stuff. I didn’t have the heart to tell her she was playing it wrong.
Willow:Wrong? Why? How did you play doctor?
Buffy:I… never have.
Mr. Whitmore:S-E-X. Sex. The sex drive in the human animal is intense. How many of us have lost countless productive hours plagued by unwanted sexual thoughts and feelings?
Xander:Yes! Mm-hm.
Mr. Whitmore:That was a rhetorical question, Mr. Harris, not a poll.
Xander:Well, you know, it’s the whole ‘sex leads to responsibility’ thing, which I personally don’t get. You gotta take care of the egg. It’s a baby. You gotta keep it safe and teach it Christian values.
Willow:My egg is Jewish.
Xander:Then teach it that Dreidel song.
Buffy: Do you want to be William the Bloody? Or just Spike? Cause, either way, it’s gonna look majorly weird.
Spike: Whereas the name Buffy gives it that touch of classic elegance.
Buffy: What’s wrong with Buffy?
Giles: Huh! Such a good question.
possibly my favorite Buffy quote:
“It has come to my attention that some viewers are upset by a character on BTVS who embraces a controversial lifestyle that is shared by, at most, 10 percent of the population. So from this moment on Willow Rosenberg will no longer be Jewish.”
–Joss Whedon
I did love this lyric in “Once More With Feeling”:
You’re the cutest of the scoobies
With your lips as red as rubies
And your firm yet supple–
Tight embrace
Cordelia: “Pardon me while I interrupt your downward mobility.”
“I have to call everybody I’ve ever met right now!”
Willow: “Hello! Gay now!”
Anya: Bunnies aren’t just cute like everybody supposes!
They’ve got them hoppy legs and twitchy little noses!
And what’s with all the carrots? What do they need such good eyesight for anyway?
Bunnies! Bunnies, it must be bunnies!
… sound of crickets…
or maybe midgets
Spike: “Randy? Randy Giles? Why didn’t you just call me Horny Giles or Ready-For-A-Shag Giles?”
same ep.
“Oh God, how I must hate you.”
Xander: “Too many girls. Oz would’ve gotten it. He wouldn’t have said anything, but he would’ve gotten it.”
Oh, no, these are my favorites:
Willow: Weird? It's against all laws of God and Man! It's ***Cordelia!*** Remember? The, the 'We Hate Cordelia' club, of which you are the treasurer!
*
--Innocence*
Giles: Unbelievable. ‘Do you like my mask? Isn’t it
pretty? It raises the dead!’ Americans!
*
–Dead Man’s Party*
Which reminds me of another fave quote…
Giles: No! I just think it’s rather odd that a nation that prides itself on its virility should feel compelled to strap on forty pounds of protective gear just in order to play rugby.
Mayor Wilkins’ diary:
Greet Scouts
Lumber Union Reschedule
Call Temp Agency
Become Invincible
Meeting With PTA
Haircut
I can’t say it is my favorite, there are way too many for that, but one I liked that has not yet been mentioned is from last year’s finale, as they leave to go fight Glory.
BUFFY: Everybody knows their jobs. Remember, the ritual starts, we all die. And I’ll kill anyone who comes near Dawn.
SPIKE: Well, not exactly the St. Crispin’s Day speech, was it?
GILES: We few, we happy few…
SPIKE: We band of buggered.
I guess as a former English poet Spike is well-versed in his Shakespeare.
Least favorite line? From too many episodes to mention, it’s Dawn with a high-pitched shriek: “Buffy!”. Although it did lead to the classic “Must be Tuesday” line, as well as veiny Willow’s great rant.
Another great Xander line is from “Inca Mummy Girl”.
They’re going to a costume party and Xander is dressed up like Clint Eastwood in from the spaghetti westerns. Buffy asks Xander where he’s supposed to be from and he says he’s from “Leone, which is in Italy pretending to be Montana.”