Raj: You can't ruin a friendship with sex. That's like ruining ice cream with chocolate sprinkles.

Amy: Before I met you, I was a mousey wallflower. But look at me now. I'm like some kind of downtown-hipster-party girl with a posse, a boyfriend and a new lace bra that hooks in the front, of all things!

Raj: I don't know if I wanna play any more.
Sheldon: Because you don't have a girlfriend? Well, good lord, if that becomes a reason to not play dungeons and dragons, this game is in serious trouble.

Penny: Amy, little vixen. Just working it under all those layers of wool and polyester.

Mary: Could the reason you can't find a guy is because you're letting them ride the rollercoaster without buying a ticket?
Penny: Oh, they don't always get to ride the roller coaster. Sometimes they only get to spin the teacups.

Sheldon: To amend the words of Toy Story, you have not got a friend in me.

Howard: Why don't I talk to him about it in May?
Bernadette: In May, you're gonna be on the International Space Station.
Howard: They got a phone.

Amy: I'm dating Sheldon Cooper
Penny: Yes. On purpose.
Amy: He's handsome, he's lanky, he's brilliant, and his skin has that pale, waxy quality.
Penny: Well, sickly is the new sexy.

Sheldon: Biologists are mean.

Penny: This girl is trouble. What kind of relationship is it where you buy her gifts and she gives you sex?
Raj: The best one I've ever had!

Leonard: You may be from Texas, but I'm from New Jersey.

Sheldon: The dice giveth and the dice taketh away.

Amy: Goodnight, painting Penny. Goodnight, real Penny.
Penny: Goodnight, real Amy.
Amy: You don't have to say goodnight to painting Amy, because she's never leaving.

Sheldon: I don't watch you twenty-four hours a day. I don't know what you do.

Sheldon: As you know, the essence of diplomacy is compromise. With that in mind, I propose the following: I will take Rothman's office... and you will find a way to be okay with that.
Barry Kripke: How about I take Rothman's office and you go suck a lemon?