Sheldon: I have noted that Leslie Winkle recently started shaving her legs. Now, given that winter is coming, one can only assume that she's signaling sexual availability.
Wolowitz: I don't know. You guys work in the same lab.
Leonard: So?
Wolowitz: There are pitfalls. Trust me, I know. When it comes to sexual harassment law, I'm a bit of a self-taught expert.
Leonard: Look Howard, if I were to ask Leslie Winkle out, it would just be for dinner. I'm not going to walk into the lab, ask her to strip naked and dance for me.
Wolowitz: Oh, then you're probably okay

[trying to assemble Penny's new wardrobe, reading the instructions]
Wolowitz: Oh, boy! I was afraid of that!
Leonard: What?
Wolowitz: These instructions are a pictographic representation of the least imaginative way to assemble these components. This, right here, is why Sweden has no space program

Sheldon: I couldn't sleep knowing that just outside my bedroom is our living room and just outside our living room is that hallway and immediately adjacent to that hallway is this! (showing Penny's messed up apartment)
Leonard: Do you realize if Penny wakes up there's no reasonable explanation to why we are here?
Sheldon: I just gave you a reasonable explanation.
Leonard: No, no. You gave me an explanation. Its reasonableness will be determined by a jury of your peers

Sheldon: You do understand that our efforts here will in no way increase the odds of you having sexual congress with this woman?
Leonard: Men do things for woman without expecting sex.
Sheldon: Those would be men who just had sex

Leonard: I guess we'll just bring it up ourselves.
Sheldon: I hardly think so.
Leonard: Why not?
Sheldon: Well, we don't have a dolly, or lifting belts, or any measurable upper-body strength.
Leonard: We don't need strength. We're physicists. We are the intellectual descendants of Archimedes. Give me a fulcrum and a lever, and I can move the Earth. (Trying to move the box) It's just a matter of... I don't have this. I don't have this. I don't have...
Sheldon: Archimedes would be so proud

Leonard: If you don't have any other plans, do you want to join us for Thai food and a Superman movie marathon?
Penny: A marathon? Wow, how many Superman movies are there?
Sheldon: You're kidding, right?

Excuse me, explain to me an organizational system where a tray of flatware on a couch is valid? Now, I'm just inferring that this is a couch, because the evidence suggests that the coffee table is having a tiny garage sale

Sheldon

Penny: So, what do you guys do around here?
Sheldon: Well, today we tried masturbating for money

[on their way to pick up Penny's TV from her ex]
Sheldon: And why can't she get her own TV?
Leonard: Come on, you know how it is with break-ups.
Sheldon: No, I don't and neither do you.
Leonard: But I -- I broke up with Joyce Kim.
Sheldon: You did not break-up with Joyce Kim, she defected to North Korea.
Leonard: To mend her broken heart

Penny: And on top of everything else, I'm all gross from moving. My stupid shower doesn't even work.
Leonard: Our shower works.
Penny: Really? Would it be totally weird if I used it?
Sheldon: Yes.
Leonard: No!
Sheldon: No?
Leonard: No.
Sheldon: No

Leonard: Sheldon, I am so sorry I dragged you through this.
Sheldon: It's ok. It wasn't my first pantsing, and it won't be my last.
Leonard: But you were right about my motives. I was hoping to establish a relationship with Penny that might have someday led to sex.
Sheldon: Well, you got me out of my pants.

Penny: I'm a vegetarian. Well, except for fish, and the occasional steak. I love steak!
Sheldon: Well, that's interesting. Leonard can't process corn

The Big Bang Theory Season 1 Quotes

Leonard: We need to widen our circle.
Sheldon: I have a very wide circle. I have 212 friends on MySpace.
Leonard: Yes, and you've never met one of them.
Sheldon: That's the beauty of it

Leonard: At least I didn't have to invent 26 dimensions just to make the math come out.
Sheldon: I didn't invent them, they are there!
Leonard: In what universe?
Sheldon: In all of them, that's the point