Penny: Wil Wheaton is Sheldon's mortal enemy.
Amy: Mortal enemy?
Penny: Mm-hmm.
Amy: Sheldon, I know you are a bit of a left-handed monkey wrench but... you really have a mortal enemy?
Sheldon: In fact, I have 61 of them.

Sheldon: The Koothrappalis aren't just rich, they're Richie Rich rich.
Penny: How much is that?
Sheldon: About halfway between Bruce Wayne and Scrooge McDuck.

Okay, so future grief-stricken widow is the one to beat.

I feel like two totally different people. Dr. Jekyyl and Mrs. Whore.

Raj: To quote Shakespeare, "It is better to have loved and lost than to stay home every night and download increasingly shameful pornography."
Penny: Oh, you poor baby!
Raj: What's wrong with me, Penny?
Penny: Nothing! Nothing. You know, if we weren't friends - and you hadn't brought up that creepy pornography story - I'd be on you like the speed of light squared on matter to make energy.

Raj: Well, to paraphrase Shakespeare: It's better to have loved and lost than to stay home every night and download increasingly shameful pornography.
Penny: Oh... you poor baby.
Raj: What's wrong with me, Penny?
Penny: Nothing, nothing. You know, if we weren't friends - and you hadn't brought up that creepy pornography story - I'd be on you like the speed of light squared on matter to make energy.
Raj: Hey, you totally got that right. E = MC squared.
Penny: I listen. I have no idea what it means, but I listen.

Penny: Oh, okay, look. THIS. NEVER. HAPPENED. Do you understand me?
Raj: (nodding)
Penny: Really?! Still can't talk to me?!

Sheldon: Here's an interesting fact about alcohol ... Man is not the only species that ferments fruit in order to become intoxicated. Can you guess what the other is? Hint: sometimes they pack the alcohol in their trunks.
Penny: Monkeys
Sheldon: When does a monkey have a trunk?
Penny: When a suitcase just won't do
Much later - Sheldon: And the answer was elephant.

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.

Bernadette: The thesis committee accepted my doctoral dissertation. I'm getting my Ph.D!!
(the other congratulate her)
Penny: Wow! So that means that....(points around the table to all the Ph.D's) You're a doctor, you're a doctor, you're a doctor, YOU'RE a doctor, and Howard....you know a lot of doctors!!

(To a box of expensive shoes she's about to take back)
Penny: I'm sorry, shoes, but you have to go back.
Shoebox (Penny): But, Penny, we love you.
Penny: I love you, too, but you cost more than my rent.
Shoebox (Penny): But Penny, you look so good in us.
Penny: (To Amy) Damn it, the shoes are right!

Priya: They dressed up in leotards and goggles and called themselves the New Delhi Power Rangers.
Penny: How old were they?
Priya: Not as old as you'd want them to be.

TBBT Quotes

Sheldon [to Kripke]: Also, I am given to understand that your mother is overweight.
Raj: Oh, snap.
Sheldon: Now of course, if that is the result of a glandular condition and not sloth and gluttony then I withdraw that comment.

How is "doable" anything but a compliment?

Wolowitz