Amy: You know, these experiments are pretty harmless. There's one where you just put the baby in front of a mirror and you watch them watch themselves.
Raj: That sounds adorable. Let me see.
Sheldon: How come when she talks about experiments on babies, you think it's adorable, but when I do it, everyone gets upset?
Leonard: I think I can speak for all of us. You're just creepy.
Howard: No offense.

Howard: You know, I'm really glad you decided to learn Mandarin.
Sheldon: Why?
Howard: Once you're fluent, you'll have a billion more people to annoy instead of me.

Bernadette: Maybe we should get one of those machines to help her up the stairs.
Howard: You mean a forklift?

Sheldon: Sheldon Cooper does not cry.
Howard: That's true, you'd rust.

Stuart: Where are the kids?
Howard: I thought they were with you.
Stuart: What? No!
Howard: I'm kidding. They're at daycare.
Stuart: What about me makes you think my heart can handle that joke?

Leonard: Just tell me the truth, Mother. Was my whole childhood just one big experiment?
Beverly Hofstadter: Of course not, dear. It was thousands of small experiments.
Leonard: So that's all I was to you, a-a test subject?
Beverly Hofstadter: No, you were my baby and I found you fascinating.
Leonard: Really?
Beverly Hofstadter: Yes, watching you develop, tracking your progress. I know I'm not the warmest of parents, but it was time we spent together, and, honestly, those are some of my fondest memories.
Leonard: When did you stop?
Beverly Hofstadter: Oh, I can't tell you. The experiment isn't over.

Raj: I never thought I would see Sheldon enjoying himself around babies so much.
Amy: Yeah, how about that?
Raj: So he just happened to stumble upon a book about experimenting with them the same day we were hanging out with Howard's kids?
Amy: Yep, don't overthink it.