Disclaimer: I didn't invent One Piece, because, quite frankly, I lack all originality and creativity, which is why I googled 'witty quotes' and made the characters of One Piece say them with a pistol pointed at their brain, pretending to call them my own.
Ace: Having a little brother who's a little on the slow side makes the older brother worry.
Luffy: And having an older brother who's a pyromaniac makes the younger brother worry.
Ace: So we're square, then?
Luffy: Not quite. You're also narcoleptic, can't swim and happen to face bounty hunters at every corner you turn.
Ace: Finished?
Luffy: Pretty much.
Robin: What happens if your parachute doesn't open?
Luffy: I've thought about that.
Robin: And?
Luffy: We'll die. See? Thought about it.
Nami: For Sale! Parachute. Only used once, never opened, small stain.
Sanji: Den Den Mushi Answering Machine: Hi. This is Sanji: If you are the phone company, I already sent the money. If you are my parents, please send money. If you are my financial aid institution, you didn't lend me enough money. If you are my friends, you owe me money. If you are a female, don't worry, I have plenty of money.
Robin: *reading book*
Luffy: Robin, books have knowledge, knowledge is power, power corrupts, corruption is a crime, and crime doesn't pay…so if you keep reading, you'll go broke.
Robin: Thank you for your wisdom, Luffy, but I don't care.
(Luffy is going undercover, although unfortunately he can't remember the name he's supposed to use as substitute to his own incase anybody asks)
Man: What's your name?
Luffy: What's your name?
Man: No, you.
Luffy: Why not you?
Man: I asked first.
Luffy: I asked second.
Man: I haven't got time for your childish games.
Luffy: Oh really, where are you headed?
Man: Stop trying to change the subject!
Luffy: I'm not!
Man: You are!
Luffy: Am not.
Man: Are too.
Luffy: Bye!
Man: What?
Luffy: You smell funny.
Drunk man: And you smell like my little doggy I left back at my old house. Mister Pickles, I think he was called. Oh, how I miss you, Mister Pickles.
Luffy: What are you talking about.
Drunk man: Don't know. Say, how about this, you buy me a beer and I give you this jar of dirt.
Luffy: Or…I run away with the jar of dirt while you despair about what you have lost.
Drunk man: Sounds fair to me.
Luffy: Okay, give me that jar of dirt or I'll kill you.
Luffy: Guard the boat, mind the tide, don't touch my dirt.
Person 1: I dream of a world where I can call everyone my friend.
Person 2: I dream of a world where I can turn my whisper into a shout.
Person 3: I dream of a world where I reach out and touch the stars.
Person 4: I dream of a world where day is equal to night.
Luffy: I dream of a world where chickens can cross the road and not be questioned about their motives.
Zoro: Are you blackmailing me?
Luffy: Don't be racist, Zoro.
(Was an actual conversation that happened at school. XD)
Ugly lady: Hey, Sanji, you're looking rather cool today.
Sanji: Thanks, you don't look so hot yourself.
Ace: Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
Luffy: Aren't we forgetting the true meaning of Christmas? You know, the birth of Santa?
Nami: Light travels faster than sound.
Zoro: That's why some people appear bright until you hear them speak.
Robin: Really, like who?
Luffy: Nami, I have a question.
Nami: What now?
Luffy: Are you telling the truth if you lie in bed?
Nami, Robin, Zoro: *face palm*
Zoro: What you just said is too stupid to put in words.
Nami: Y' know what?
Robin: What?
Nami: The world's just getting stupider and stupider.
Robin: Not everyone will fit into that stereotype, Nami.
Nami: Oh really? I went into McDonalds today and asked for some fries. The lady at the counter said 'would you like fries with that?'
Sanji: Baby, did you fart?
Woman: What?
Sanji: 'Cause you blow me away!
Nami: Damn, I need a drink.
Sanji: What do you want? Coffee? Tea? Me?
Man: Where is he?
Usopp: I'll never tell!
Man: Tell me!
Usopp: Death before Dishonour!
Man: Tell me, or I'll chop it off!
Usopp: You mean…it?
Man: Yes, it!
Usopp: When I said Death before Dishonour, I meant it alphabetically
Luffy: Set sail to…erm…that way!
Robin: Where are we going?
Luffy:
I refuse to answer that question on the grounds that I don't know the answer.
Robin: I understand that you once visited the Amanilands?
Luffy: Yes indeed. Nice bunch, they were, the Amanis. Even went through the trouble of waving to me when I set sail once again…with all five fingers, of course.