[Sheldon is discussing Leonard's failed relationships with Penny]
Sheldon: So what is the "down" and the "low", and don't worry, this is all entirely confidential, so you feel free to include any and all shortcomings in the bedroom.
Penny: We never got to the bedroom.
Sheldon: Because...?
Penny: OK, all right, you know what? I'll tell you what happened. We were young, we were very much in love, but we could only communicate through a time-traveling mailbox at my lake house.
Sheldon: It's not enough that you made me watch that movie, but now you mock me with it?!

[Sheldon is talking to a potential mate for Penny]
Sheldon: Excuse me. Are you currently involved in a sexual relationship?
Blaine: No?
Sheldon: Would you like to be?
[Leonard and Leslie look shocked and amused as they realise what's happening]
Blaine: Uh... Sure, why not?
Leonard: Sheldon -
Sheldon: [silences him] Can I have your phone number?
Blaine: [looks him up and down] Err... Yeah.
[A little too eagerly, he grabs Sheldon's hand and writes his number on his palm]

[Sheldon is trying Howard's driving simulator - with disastrous results]
Leonard: How did you manage to get on the second floor of the Glendale Galleria?
Sheldon: I don't know, I was on the Pasadena Freeway, missed my exit, flew off the overpass and...one thing led to another.
[Screeching tires are heard from the simulator, followed by a crash and barking and meowing]
Leonard: Awwwwww, the pet store��
Sheldon: Remind me to compliment Wolowitz on the software, it's amazingly detailed.

[the guys are playing Klingon Boggle]
Howard: I have "chor" [Klingon for "belly"]
Sheldon & Raj: Got it.
Howard: "neHmaH" [Klingon for "neutral zone"]
Sheldon & Raj: Yep.
Howard: And "Kreplach".
Raj: Hold on a second, "Kreplach"?
Howard: Yeah.
Raj: That isn't Klingon, it's Yiddish for a meat-filled dumpling!
Howard: Well, as it turns out, it's also a Klingon word.
Leonard: Really? Define it.
Howard: Kreplach: a hearty, Klingon��dumpling.
Raj: Judge's ruling?
Sheldon: [makes thumbs-down gesture] bIlughbe' [Klingon for "you are not right"]

[Upon hearing that Leonard, Wolowitz, and Raj are upstairs in the new girl's apartment]
Penny: Typical.
Sheldon: It's axiomatically atypical. Up until recently they did not know Alicia, and had no encounters with her in her previous location. They never went upstairs to visit the former tenants. So your characterization of their behavior as typical is demonstrably fallacious.
Penny: [referring to his earlier impersonation of Admiral Ackbar] OK, now I see the squid head.

[Penny knocks on the door]
Penny: Merry Christmas!
Leonard: Merry Christmas!
Penny: How's your leg?
Leonard: Very good. Thanks for asking. Come on in.
Sheldon: Oh good, Penny, you're here to exchange gifts. You'll be pleased to know that I'm prepared for whatever you have to offer.
Penny: [handing Sheldon his present] Ok, here.
Sheldon: Hmmm. [starts to open his present] I should note, I'm having some digestive distress, [Leonard shakes his head no] so if I excuse myself abruptly, don't be alarmed. [completes opening his present] Oh! A napkin.
Penny: Turn it over!
Sheldon: [becomes weak at the knees and has to sit down as he reads] "To Sheldon. Live long and prosper. Leonard Nimoy."
Penny: He came into the restaurant. Sorry the napkin's dirty, he wiped his mouth with it.
Sheldon: [gasps] I possess the DNA of Leonard Nimoy?!
Penny: Well��yeah, I guess. But look, he signed it!
Sheldon: [visibly shaking] Do you realize what this means?!?! All I need is a healthy ovum and I can grow my own Leonard Nimoy!
Penny: Okay, all I'm giving you is the napkin, Sheldon.