Sheldon: Are we all up to date on our yellow fever inoculations?
Howard: You don't need a yellow fever shot to go to Mexico.
Sheldon: You can never be too careful. I got one last year before I went to Epcot.

Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Sheldon: Why are you crying?
Penny: Because I'm stupid.
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

Penny: What are you doing back?
Leonard: We got a flat and couldn't get the tire off.
Penny: Oh, I'm sorry.
Leonard: Thank you.
Penny: If it makes you feel any better, I pierced Amy's ears and her mom made her sit in my closet.
Sheldon: We blew up Feynman's van.
Penny: My dad killed my pig with his tractor.
Leonard: I spent the night in Mexico with Sheldon.
Penny: You win.

Amy: Uh, well, actually, to be honest I haven't told her yet.
Penny: You've been giving me a hard time and you haven't even told your mom about Sheldon?
Amy: I'm feeling a little dizzy from all the blood loss. I don't know what you're talking about.

Penny: Thanks a lot, guys.
Bernadette: What did we do?
Penny: Before I made that call, my pig was alive and happy and rolling around in the mud. Now he's illegally buried in our backyard next to my great-grandmother.
Bernadette: Really? They didn't eat him?
Penny: No! He was a beloved member of the family.
Bernadette: The breakfast meat family?