Amy: What are you going as?
Howard: I don't want to ruin the surprise. You'll see it at work. Just a warning: it's pretty scary.
Sheldon: Is it a bird?
Howard: No.
Sheldon: Is it a dog?
Howard: No.
Sheldon: Oh, I think I'll be fine, then.

Leonard: Are you gonna dress in drag in front of your fiancee?
Raj: Yeah. We have no secrets from each other. Well, except for the fact that I crocheted this myself.

Leonard: Sheldon, he's being you. He's dressed as you for Halloween.
Sheldon: Oh. So you're not laughing at him. You're laughing at me.
Raj: We're not laughing at you. We're laughing with you.
Sheldon: But I'm not laughing.
Raj: Then the first one.

Leonard: Hey, happy Halloween.
Penny: Oh! Trick or treat.
Leonard: No. Sorry, you're not wearing a costume.
Penny: Yeah, I am. I'm a pharmaceutical sales rep.
Leonard: I'm gonna need more.
Penny: Okay, failed actress who traded constant rejection for a Christmas bonus and a dental plan?
Leonard: Go nuts.
Penny: Oh. I will.

Leonard: So, what are you wearing to the party? Sexy cat? Sexy nurse? Sexy zombie?
Penny: Why do girls' costumes have to be sexy but guys' costumes don't?
Leonard: (scoffs) Say that again with this helicopter on my head.
Penny: Very cute.

Penny: You're not mad at me, are you?
Leonard: No. Of course not. No, we just remember different things from that party. I remember falling in love, and you remember vomiting in a pumpkin.
Penny: I was, like, four feet away. People cheered.

Bernadette: Anyway, the point is, Sheldon shouldn't dish it out if he can't take it.
Amy: I think the point is that Howard owes him an apology.
Bernadette: Yeah, well, I think the point is if Sheldon has a problem with Howard, Sheldon should take it up with him. Now, if you'll excuse me, the prime minister of England needs her diaper changed.

Leonard: Oh, that's great. He's a Supreme Court justice, and you're the U.S. Constitution.
Anu: Yep. He interprets me. And guess what's underneath this? The Bill of Tights.

Bernadette: Hey, Bert, what are you dressed as?
Bert: I'll give you a hint. My work in seismic refraction measurements and-
Bernadette: Hey, Stuart, what are you dressed as?
Stuart: I'm a butterfly.
Bernadette: Did you steal those from Halley's "let's pretend" box?
Stuart: I'm gonna put them back.

Bert: All right, I'll tell you. I'm Maurice "Doc" Ewing, winner of the 1960 Vetlesen Prize, generally regarded as the Nobel Prize of geology.
Bernadette: Oh, yeah. Now I see it.
Bert: Ask me how I died. Spoiler alert: brain hemorrhage.

Leonard: So, here we are. On Halloween. On this couch. Does it ring any bells?
Penny: Really? We're still doing this?
Leonard: I'm just surprised you don't remember our first kiss.
Penny: (sighs) Fine. It was on Halloween.
Leonard: Are you agreeing just to shut me up?
Penny: You got another way? I'm all ears.

Bert: Really? An arranged marriage?
Raj: Yeah. I know how it sounds.
Bert: It sounds awesome. Is that just an Indian thing, or can I get a piece of that?
Anu: You know the woman has a choice, right?
Bert: There's always a catch.

Leonard: Okay, guys, I think that's enough.
Raj: Hold on. I'm the judge here, and I'm going to allow it.
Penny: Raj, take a break.
Anu: Hey, free speech. Right back there somewhere.

Howard: You know what, guys? You got us. Congratulations. Now why don't you go back to your apartment and put on your other costumes.
Amy: Oh, but it's so far away, and I have such teeny, tiny legs.

Bert: I don't get invited to a lot of parties. Is this a good one?
Stuart: Oh, yeah.