Sheldon: Would you like to play a physics car game I invented called "I Can't Spy"? It's all the nail biting tension of "I Spy," but the added fun of sub-atomic particles and waves outside the visible spectrum.
Leonard: If it's half as much fun as "One Times Ten to the Fourth Bottles of Beer on the Wall," I'm in.

We won't know if there's equality until female Thor has a baby, and the avengers are cool with her pumping breast milk at work.

Amy

Bernadette: Did she throw anything away?
Howard: Nope. If I find my foreskin, I'm gonna kill myself.

Oh, please. I have ideas all day long. Reverse Sea World, where dolphins are allowed to pet people. A new clothing size in between medium and large, called "marge." Snow White retold from the point of view of Sneezy. Why won't Doc prescribe him something? We finally find out.

Sheldon

Penny: I mean, who even reads Scientific American.
Leonard: It's kind of a big deal.
Penny: If it's such a big deal, how come the biggest celebrity they could get for the cover is a molecule?

Okay, then, how about this. Let's invite everyone over to dinner. It'll be like Ma's feeding us one last time.

Howard

While my brother was getting an STD, I was getting a PhD.

Sheldon

Leonard: And we weren't even watching TV! We were watching Netflix like the kids do!
Penny: Yeah! Is it a comedy? Is it a drama? Nobody knows!

Bernadette: A two-hundred dollar R2D2 is a business expense?
Howard: Oh, Bernie. You're gonna have to sound a lot more confident when we get audited.

Leonard: It comes with paints and it's kind of creative and artistic.
Penny: Okay, did you go to the dirty store, or Michaels?

Penny: See, this is why I've been saying we should keep champagne on ice.
Sheldon: Sarcasm?
Amy: Yes.
Sheldon: That was tricky because when it comes to alcohol she generally means business.

Amy: After a careful evaluation of our relationship. We decided that the time was right to take a step forward.
Leonard: Okay.
Sheldon: Do you want to say it?
Amy: Let's say it together!
Sheldon and Amy: We're getting a turtle!

TBBT Quotes

Mrs. Cooper: Shelly! I'm so glad you're here!
Sheldon: I saw you having naked sex.

Penny: Here's a question-- as an alien pretending to be human, are you planning to engage in any post-prom mating rituals with Amy?
Sheldon: There are post-prom mating rituals?
Penny: Not always. Unless your date drives a van with an air mattress, then always.
Sheldon: Well, if it's part of the prom experience, then I'm open to it.
Penny: You're kidding.
Sheldon: I may be an alien, but I have urges.If Amy wants to copulate by firing her eggs into space, well, then, I will happily catch them with the reproductive sac on my upper flermin. I'm not the best at reading facial cues, but I can see that you're a little turned on.