Sheldon: My mother believes I'm mentally unstable. And since there's a genetic component and I'm her child, I suppose it's possible.
Mary: I know you're angry right now, but you will not be disrespectful.
Sheldon: You know, fits of rage are a classic sign of psychosis.
Mary: Oh, you haven't seen fits of rage yet!

Sheldon: Regardless, I'm not interested in making any more friends.
Mary: Oh, I don't think that's how you really feel.
Sheldon: It is. From now on, it's a hermit's life for me.
Mary: I bet, when you grow up, you will be surrounded by lots of smart, wonderful friends.
Sheldon: I can't see that happening.

Sheldon: Mom, when should I be expecting my testicles?
Woman: [turns around] What is wrong with him?
Mary: Nothing is wrong with him. Now turn around before I knock your lights out.
Sheldon: Hello.

Sheldon: And then they laughed at me for not knowing something that they knew. Who does that?
Mary: You do.
Sheldon: Well, this is no time for a teachable moment. Your child is hurting.
Mary: Sorry. [taps Sheldon's shoulder] There, there.
Sheldon: I guess that'll do. Now, how about a hot beverage?

Mary: I was just letting you know that if you were having any problems you could come to me with them.
Sheldon: You think I have mental problems?
Mary: Well, not problems. I'm just worried about your future, and when I see you moving subatomic particles around in the air, that makes-
Sheldon: Subatomic particles are real! You talk to an invisible man in the sky who grants wishes. If anyone's mental, it's you.

Sheldon: Why aren't you also driving Missy to school?
Mary: I thought it might be nice for us to chat.
Sheldon: About Missy? She is a bit much, isn't she?

Mary: Here's a question for you. Do you ever see or hear things that other people can't?
Sheldon: Oh, all the time. Right now, the car antenna is vibrating at the same frequency as the pistons in the motor. It's quite irritating, but you know me I don't complain.
Mary: I meant more like things that aren't actually there.
Sheldon: Ah, isn't that the fundamental question of modern metaphysics? What is actually there? This is fun. Missy should ride with Dad more often.