Leonard: Because you don't know how to do cryptanalysis, do you?
Howard: I'm not even sure if it's the right word.

Leonard: What if... what if this is the thing that would've finally let him open that bottle of champagne?
Raj: Maybe he didn't know what to pair champagne with. Strawberries, caviar, oysters. All good choices. Yeah, that look right there is why people eat before they come to your parties.

Raj: When stuff like this gets me down, you know what I like to do?
Howard: Sing "Hakuna Matata" like an eight-year-old girl?
Raj: Wrong, smarty-pants. It's "Everything Is Awesome" from The Lego Movie.

Amy: Say, Betsy Ross, what you working on?
Sheldon as Betsy Ross: I have no idea. Because the story of me sewing the first American flag is unsupported poppycock.
Amy: Then who did sew it, hmm?
Sheldon as Betsy Ross: Don't ask me. I'm just a simple seamstress whose descendants are...out to make a quick buck!

Dan: Bernadette. Cute, sweet...vicious little Bernadette.
Penny: Come on. She's not that bad.
Dan: Oh, yeah? At the company picnic she yelled at me and my grandson for losing the three-legged race. I mean, he still calls her "that mean kid with the big boobies."

Raj: This old pen kind of proves gravity. When I tilt it, her bathing suit falls right off.
Howard: Oh, my dad used to have a pen like that. I dated it all through sixth grade.

You know, I thought cleaning out a dead professor's office was gonna just be boring, but then I found his dentures and realized it's also gross.

Raj

Sheldon: Now, I'm sure you're thinking, "The final episode? Who will stand between us and flag ignorance""
Amy: I know I was thinking that. Is this a show on flags or mind reading?
Sheldon: But the truth is I can no longer balance a full-time career, a popular Internet show, and a girlfriend.
Amy: And he really does have one, you jerks on the comment board. So as they say, all good things must come to an end.

I can't send it back. I had it engraved. "Here lie the ashes of Leonard Hofstadter. He thought he was right, but his roommate knew better."

Sheldon

Leonard: Okay, first of all, the surgery was a success, and secondly, I didn't even want you there.
Sheldon: Wow. I don't know which hurts worse-- my nose or my heart.

Penny: Okay, the reason he deceived you is you were being
a pain in the ass.
Sheldon: The reason I was being a pain in the B is because I was worried about him, and no one else was.
Penny: Really? You won't even say "A"?
Sheldon: You bet your sweet B I won't.

Sheldon: I assume this medical center's already treated the burns on your bottom from the recent pants fire.
Penny: 'Cause I'm a liar, liar?
Sheldon: That's for the fire marshal to determine.

TBBT Quotes

Sheldon: I recently read that during World War Two, Joseph Stalin had a research program to create supersoldiers by having women impregnated by gorillas.
Howard: What a sick use of science.
Raj: Hey, as long as the baby's healthy.
Amy: I wonder if Stalin considered any other animals.
Leonard: Hippos are the deadliest creature. A half-human, half-hippo soldier would be pretty badass.
Howard: Yes, but when they're hungry-hungry, you can stop them with marbles.
Sheldon: Yeah, the correct animal for interspecies supersolider is koala. You would wind up with an army so cute it couldn't be attacked.

Raj: Well, to paraphrase Shakespeare: It's better to have loved and lost than to stay home every night and download increasingly shameful pornography.
Penny: Oh... you poor baby.
Raj: What's wrong with me, Penny?
Penny: Nothing, nothing. You know, if we weren't friends - and you hadn't brought up that creepy pornography story - I'd be on you like the speed of light squared on matter to make energy.
Raj: Hey, you totally got that right. E = MC squared.
Penny: I listen. I have no idea what it means, but I listen.