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.

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.

Stuart: Oh, Sheldon, I'm afraid you couldn't be more wrong.
Sheldon: More wrong? Wrong is an absolute state and not subject to gradation.
Stuart: Of course it is. It's a little wrong to say a tomato is a vegetable, it's very wrong to say it's a suspension bridge.

Sheldon: I feel renewed. I'm ready to deal with any changes that come my way. [sees Penny] Your hair is different. You changed your hair. I can't take this. I'm out.

Sheldon: My friends and I couldn't get into Comic-Con this year, and I was trying to start my own convention, and I was going to ask if you'd be a panelist.
James Earl Jones: Why don't you and your friends come to Comic-Con with me?
Sheldon: Really?
James Earl Jones: Of course. And San Diego is straight across the border from my favorite city on earth, TIJUANA! Where I'm taking you every night!
Sheldon: Ay-ay-ay.
James Earl Jones: Ay-ay-ay bang bang!

Mary Cooper: Thank you, God, for the food we are about to receive and for the nourishment of our bodies and bless the hands that prepared it. Amen.
Sheldon: Given that your hands prepared it, isn't that a little self-serving?
Mary Cooper: You start changing the words to the prayers, next thing you know, you're in a church with a guitar.

Amy: Do you need anything else?
Sheldon: You know exactly what I need.
Amy: Fine. [sings and plays autoharp] Soft kitty, warm kitty, little ball of fur. Happy kitty, sleepy kitty, purr, purr, purr.
Sheldon: That's nice. Now in German.
Amy: [sings and plays autoharp] Weiches Kätzchen, warmes Kätzchen, das nie und nimmer murrt. Liebes Kätzchen, müdes Kätzchen, schnurrt, schnurrt, schnurrt.
Sheldon: Great. Now Mandarin.
Amy: [sings and plays autoharp] Ruǎnmiánmián de xiǎo māomī máoróngrōng, kuàilè kēshuì qīngqiǎo māomī, gūlǔ gūlǔ gūlǔ.
Sheldon: Now Navajo.