Sheldon: (knocking) All my friends. (knocking) All my friends. (knocking) All my friends.
Howard: Wow, I think it's like Beetlejuice. We must've said his name too many times.

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.

Josh: So, I have to ask, was the robot sexy?
Howard: It was actually just a mechanical hand.
Josh: 'Cause that's all you need, right?
Howard: You are my brother.

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

Sheldon: Jacuzzi is a commercial brand, hot tub is the generic term, i.e., all Jacuzzis are hot tubs, but not all hot tubs are Jacuzzis.
Zack: Is that like all thumbs are fingers but not all fingers are thumbs?
Sheldon: Surprisingly, yes.
Zack: Nice! Now what exactly are toes?

Wolowitz: Raj, did you ever tell your sister about the time Sheldon got punched by Bill Gates?
Priya: Oh, God, you're kidding.
Raj: No, Gates gave a speech at the university. Sheldon went up to him afterwards and said, "Maybe if you weren't so distracted by sick children in Africa you could have put a little more thought into Windows Vista."
Leonard: Bam, right in the nose. Made me proud to own a PC.

Sheldon:He'll be back.
Leonard: (Through the door) Of course, I'll be back, I live here!