Leonard: How could you just sit there and let them spy on me?
Sheldon: They were very smart. They used my complete lack of interest in what you are doing.

Penny: Sheldon, could I ask you a question?
Sheldon: I would prefer that you not, but I wouldn't go so far as to forbid it.

Sheldon: I wouldn't tell you the secret. Sssh!
Leonard: What secret? Tell me the secret.
Sheldon: Mom smokes in the car. Jesus is okay with it, but we can't tell dad.
Leonard: Not that secret, the other secret.
Sheldon: I'm Batman! Ssssh!

Raj: Tag, you're it!
Howard: Shouldn't you put him in a brown paper bag and set him on fire?

Raj: They don't care for it if you stare at them and hyperventilate. Sadly, that's my homerun swing.

Raj: He was a lot more fun when he had no hope.
Howard: Give him time.

Penny: I meant has he ever been involved with someone who wasn't a brainiac?
Sheldon: Oh! Well, a few years ago, he did go out with a woman who had a Ph.D in French Literature.
Penny: How is that not a brainiac?
Sheldon: Well, for one thing she was French.

Penny: Look, just forget I told you about me not graduating from community college, okay?
Sheldon: Forget? You want me to forget? This mind does not forget. I haven't forgotten a thing since the day my mother stopped breast-feeding me. It was a drizzly Tuesday.

Raj: I hate trains.
Sheldon: Oh, don't be silly. You love trains.

Mrs. Wolowitz:What's going on? Are you boys rough housing?
Howard: We're just talking, Ma!
Mrs. Wolowitz: If you don't settle down right now, I'm not gonna let you have any more sleepovers.
Howard: For God's Sake, Ma, I'm 27 years old. And it's not even a school night.

Leonard: Penny thinks I'm too smart for her. That's ridiculous!
Sheldon: I know! Most of your work is extremely derivative. And don't worry, that's not a secret.

Penny: It's just this is only our first date.
Leonard: Well, why don't we just figure out where we're going, and when we want to get there, and then rate of speed equals distance over time, solve for 'r'.
Penny: Or we could just wing it.

Sheldon: I'm baaaaaaaaaaaaaaaack.

Mrs. Wolowitz What's going on? Are you boys roughhousing?
Howard: We're just talking, ma.
Mrs. Wolowitz If you don't settle down right now, I'm not going to let you have any more sleepovers.