[Howard playing keyboard in bed with headphones, making a clacking noise]
Bernadette: What is happening?
Howard: I was trying not to wake you.
Bernadette: Did it work?

Howard: I'm sorry I didn't take you to the airport. I just want you to know I'll never forgive myself for being so selfish. And I promise to keep you close for the rest of my life.
Bernadette: Oh, no, that thing's gonna end up in my bedroom.

Bernadette: (Shouting from the bathroom) How many times do I have to tell you to replace the toilet paper when it's empty?
Howard: I'm in the middle of something.
Bernadette: So am I!

Bernadette: Gosh, Amy. I'm sensing a little hostility. Is it maybe because like Sheldon's work, your sex life is also theoretical?

Howard: (singing) Alone in my temple in the middle of Peru, A giant stone ball with nothing to do,
Raj: But if you steal my idol, I will roll right over you
All: Cause I'm six tons of granite, And micaceous schist. Yeah, I'm six tons of granite, And micaceous schist,
Bert: I'm gonna crush you, I'm gonna mush you, You took my idol, I'm homicidal, Gonna roll over you till your brains come out, And your bones will crunch and your blood will spout! I'm not just a rock, baby. I'm a boulder.
All: Cause I'm six tons of granite, And micaceous schist. Yeah, I'm six tons of granite, And micaceous schist, Yeah, I'm six tons of granite-

Howard: What up, my Hebrews and She-brews?!

Leonard: Thought you were getting us dinner.
Penny: Sorry. I had to stop at Sheldon's and help him solve string theory.
Amy: What?
Penny: Yeah, turns out the answer's knots.
Leonard: That's cute, but you can't have knots in more than four dimensions.
Penny: Mmm ... you can if you consider them sheets. [chuckling] Good night.