Sheldon: Howard, what pocket watch will you be wearing for dinner on the train?
Howard: I'm sorry, what?
Sheldon: Well, I'm afraid if we wear the same pocket watch it will be embarrassing.
Howard: I don't own a pocketwatch.
Sheldon: Oh, my. Well my apologies for bringing up this sore spot.

Raj: If you want to solve the mystery of who stabbed Koothrappali in the back with a weapon of indifference, it was all of you!

Sheldon: I own nine pairs of pants.
Penny: Okay, that's a good start. But I was thinking something a bit more personal.
Sheldon: Oh, okay. I own nine pairs of underpants.

Raj: I mean, if I were hitting on you, you’d know it 'cause you'd feel uncomfortable and a little sad for me.

Leonard: Sheldon, it's not a great time. What do you want?
Sheldon: (on the phone in the apartment) Hello to you, too. I'm sorry, but this is important.
Leonard: What is it?
Sheldon: Back to the Future II was in the Back to the Future III case, and Back to the Future III was, get this, in the Back to the Future II case.
Leonard: So?
Sheldon: So, did you do that, or am I in the house with an intruder?

Penny: What's the matter?
Sheldon: Um, well, I was worried that you might be missing Leonard. And that might be causing you to have bad dreams, like the kind you'd get if you watched Clash of the Titans right before you went to bed.
Penny: Sweetie, did you have a bad dream?
Sheldon: To be honest, I did.
Penny: Aww.
Sheldon: Back to the Future II was in the Back to the Future III case. Leonard did it.

Sheldon: Dear Lord, you're an astronomer. Although you may have earthly woes, get your mind back on the stars. Gee, even the lowly dung beetle chooses to plot its course by using the Milky Way.
Raj: Is that true?
Sheldon: Everything I say is true. Now, of course, the dung beetle also enjoys eating feces, living in feces and making little balls out of feces, so, you know, pick and choose which aspects of its lifestyle you want to embrace.

Penny: Why don't you just admit you only want to play this game because you always play it with Leonard and you miss him?
Sheldon: You overestimate his significance in my life. Do I miss how he makes a face on my toaster waffle with syrup? No. Do I miss the way he fixes the zipper on my jacket when it gets stuck? I don't think so. Do I miss how we say good night to each other through the walls of our bedroom using Morse code? (taps out "no" in morse code)

Sheldon: By the way, how are you with zippers?
Penny: Why?
Sheldon: Well, I really need to go to the bathroom, and this ones gone all cattywampus.

Howard: Check it out. Mrs. Davis from Human Resources is here. She's probably on the lookout for sexual harassment.
Raj: Oh, great. There go my chances of being sexually harassed.

Penny: This is ridiculous. Why am I upset just because hes off having a good time?
Sheldon: Well, perhaps you're obsessively picturing him engaged in drunken coitus with another woman. Is that it? Did I get it right?
Penny: Okay, that- that's great. You can stop trying to make me feel better now.
Sheldon: Actually, I can't. Before Leonard left, he made me promise that I'd take care of you.
Penny: He did?
Sheldon: Yes.
Penny: Oh, that's really sweet.
Sheldon: Plus, if I do a good job, he said he'd bring me back a Sailor's cap.

Penny: Okay, look, here's something people do not know about me. When I first moved out to L.A., I did a topless scene in a low-budget horror movie about a killer gorilla. Ugh, after I did it, I felt so ashamed. Thankfully, that thing never came out.
Sheldon: I've seen that. Yeah. "Serial Apeist". Howard found it online the day we met you.
Penny: Oh, God.
Sheldon: And it was literally the moment you walked out the door.

Sheldon: Penny, it's your lucky day. Three of these eggs are clearly not jumbo size. Grab your keys!

Sheldon: Stuart, I was wondering if you can help me find something.
Stuart: Happy to, unless it's hope or a reason to live?
Sheldon: Oh, you make me laugh, sad clown.

Sheldon: Aquaman? This isn't a gag gift, Stuart.