Aang: "...Would you like to go penguin sledding with me?"
Aang: "Everything freezes in there!"
Katara: "Let us leave!"
Bumi: "Lettuce Leaf?"
Aang: "Don't worry, Sokka - where we're going, you won't need any pants!"
Sokka: "I'm sorry, I treated you like a girl when I should be treating you like a warrior..."
Suki: "I am a warrior. But I'm a girl too."
Sokka: "I don't care what Aunt Wu says, YOU HAVE TO TAKE A BATH SOMETIME!!"
Zuko: "If you find them I'll consider the damage to my ship paid for."
June: "Heh. Forget it."
Iroh: "Plus we'll pay your weight in gold!"
June: "Make it your weight in gold and we got a deal."
Zuko: "For the last time, I'm not playing the tsungi horn."
Warden: Tell me exactly what you saw.
Officer: Well, Sir, it looked like a flying bison.
Warden: What?
Guard: It was a giant flying buffalo, Sir, with an empty saddle.
Warden: Which was it? A buffalo or a bison?
Officer: Uh, I'm not sure what the difference is, but that's not really the point is it, Sir?
Warden (angry): I'll decide what the point is, fool!
(Warden throws the man overboard)
Warden: You! Wake up the Captain. Search the entire rig!
Guard: Sir?
Warden: What!?
Guard: That was the Captain you just threw overboard, sir.
Warden: Then wake up someone I haven't thrown overboard and search the rig! There's something going on here and I don't like it.
Book 2
Wizard: "You are wearing a ceremonial dress from each of the four bending nations! [...] Water! Earth! Fire! Air! FOUR ELEMENTS TOGETHER AS ONE!..."
Aang: "...This is just mud!"
Chong: (sings) "Two lovers, forbidded from one another / A war divides their people / And the mountains divide them apart... (speaks) I forget the next line but the chorus goes (sings) SECRET TUNNEL! SECRET TUNNEL! Through the mountains, secret secret secret secret TUNNEL!"
[later]
Chong: "Hey, I remember the last line now!" (plays) "And diiiieeee...."
Katara: (To Sokka) "Why's your forehead all red?"
Chong: "Nobody react to what I'm about to tell you... but I think that kid might be the Avatar."
Sokka: (facepalm, explaining the mark)
("Avatar Day" opens with Sokka losing his boomerang in the Rough Rhinos attack)
Sokka: "I feel like I've lost a part of my identity.. it's like, if you lost your arrow, or Katara lost her... hair-loopies."
Shopkeeper: "Here you go, ponytail-guy."
Sokka: (sigh) "I used to be boomerang-guy..."
The Boulder: "The Boulder feels conflicted about fighting a young, blind girl."
Toph: "Sounds to me like you're scared, Boulder!"
The Boulder: "The Boulder is over his conflicted feelings and is ready to bury you IN A ROCK-A-LANCHE!!"
Toph: "Whenever you're ready, The Pebble!"
Katara: "You've been hallucinating off cactus juice all day, and now you just lick something stuck to the wall of a cave?!"
Sokka: "I have a natural curiosity."
Book 3
Aang: "I can't believe we forgot Toph can't write!"
Sokka: "Yup, we're idiots."
Aang: "I guess Plan B is, we send a note to Toph saying it's from Katara."
Sokka: "I think we're gonna run into a similar problem."
Sokka: "Great. So we'll just use your new dance moves and tapdance our way to victory over the Fire Lord."
Zuko: "It's not a dance. It's a sacred Firebending form."
Katara: "Oh yeah? And what is this 'sacred' firebending form called?"
Zuko: "...the Dancing Dragon."
Warden: "The prisoners are escaping! Guards! Capture them and throw them in the cooler!"
Guard: "Uh, they are in a cooler, sir."
Warden: "One that's bolted down and not floating in the water!"
Azula: "The thing I don't understand is why? Why would you do it? You know the consequences."