Raj: Lock up your daughters, we're going to hit it and quit it.

Howard: Gather around, kids. It's time for Sheldon's beloved Christmas special.
Sheldon: In the pre-Christian era, as the winter solstice approached and the plants died, pagans brought evergreen boughs into their homes as an act of sympathetic magic, intended to guard the life essences of the plants until spring. This custom was later appropriated by Northern Europeans and eventually it becomes the so-called Christmas tree.
Howard: And that, Charlie Brown, is what boredom is all about.

Wolowitz: Qu'est-ce que 'sup?

Penny: Oh, I didn’t tell you? You’re banished from the Cheesecake Factory.
Sheldon: Why?
Penny: Well, you have three strikes. One, coming in. Two, sitting down. And three, I don’t like your attitude.

Penny: I'll tell you what happened. (sigh) We were young. We were very much in love, but we could only communicate through a time-travelling mailbox at my lake house.
Sheldon: It's not enough that you made me watch that movie, but now you mock me with it?

Dr.Gablehauser: Need to get that, Dr. Cooper?
Sheldon: God, no.
Leslie: Don't turn it off, you might miss the Nobel Prize Committee saying that you won "Dumbass Scientist of the Year."

Penny: Look, Sheldon, I'm really, really sorry but it's only going to be for a week. Can't you be a little bit flexible?
[Leonard, Howard, Raj and Sheldon all look at her]
Penny: Yeah, sorry, I didn't really think that through.

Penny: I was in junior rodeo. I can hog-tie and castrate him in 60 seconds.

Sheldon: (On computer screen) Hello, puny insects, as a consequence of your efforts to circumvent my will, everyone is awarded one additional strike.
Leonard: Thanks a lot, Howard.
Howard: What are you complaining about? I'm the one who has to take the class again.

Sheldon: Oh, Penny. I know you think you're being generous, but the foundation of gift-giving is reciprocity. You haven't given me a gift, you've given me an obligation.
Howard: Don't feel bad, Penny. It's a classic rookie mistake. My first Hanukkah with Sheldon, he yelled at me for eight nights.

Sheldon: Hey! Look I found my missing neutrino.
Howard: Oh, great! We can take it off the milk carton.

Penny: Where are my clothes?
Sheldon: Your clothes?
Penny: Yes. I left them in the washers and when I went down to get them, they were gone.
Sheldon: Really? Despite the sign that says: "Do not leave laundry unattended?"

Sheldon: Look on the bright side.
Leonard: What's the bright side?
Sheldon: Only 9 more months to Comic-Con.

Sheldon: Why don't you just take your clothes down to the river and beat them with a rock.

Howard: (Answering phone) You've reached "Friends with Benefits", for a booty call, press 1 now.