Penny: I love you.
Leonard: I love you, too.

Penny: Oh, I don't know. Remember what happened when I took care of your goldfish?
Leonard: Well, flush Sheldon down the toilet and get me a new one.

Penny: On a ship? Aren't they afraid Hawking will just roll overboard?
Leonard: Uh, he's not gonna be there. He's just sending a team to research his theory.
Penny: Oh sure. Like when you send me to kill spiders in your bathtub.

Leonard: I know what you are doing. You don't want me going on this research trip because you're afraid to be alone.
Sheldon: I'm not afraid to be alone. On the sea, it would be terrifying. Because of all the drowning.

Penny: This isn't alcohol. It's a potion that makes me like you.
Leonard: Double potion, please.

Sheldon: It would -- fun? Yeah, okay, three weeks ago, you brought crunchy peanut butter but now you want the girls to play D & D -- do you have a drug problem?
Leonard: What's the big deal?

Leonard: See, Howard is just as good a dungeon master as I am.
Sheldon: As good? You just got pantsed in the school yard four eyes.

Leonard: Sometimes change is good. You were worried about Zachary Quinto being the new Spock, but you ended up liking him.
Sheldon: Leonard, please, every time the topic of change comes up you throw Zachary Quinto in my face. I'm upset the mailman has a new haircut -- Zachary Quinto. I'm upset daylight savings time started -- Zachary Quinto. I'm upset daylight savings time ended -- Zachary Quinto. I'm saying this for the last time. Zachary Quinto was a weird, wonderful, unrepeatable event, so stop using him against me.

Professor Proton: I'm having trouble with my pacemaker.
Leonard: I'll call for help.
Penny: Any chance we could plug it into the potato?
Professor Proton: No.

Professor Proton: Is the blond girl really your girlfriend?
Leonard: Yes, sir.
Professor Proton: You're the genius.

Sheldon: Leonard?
Leonard: What?
Sheldon: I still can't sleep.

Howard: How'd you get him to come to your house?
Sheldon: As Professor Proton says, "There is no problem you can't solve if you use your noggin."
Leonard: And, he wrote him a check.
Sheldon: Yeah, that too. A big check.

TBBT Quotes

It's very simple. Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and, as it always has, rock crushes scissors

Sheldon

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.