Penny: That's amazing.
Sheldon: I wouldn't say amazing. At best it's a modest leap forward from the basic technology that gave us Country Bear Jamboree.
Howard: Hey, Sheldon? Ahem.
Sheldon: Yes?
*Howard commands the robot arm to perform a hand gesture*
Sheldon: Peace?
Howard: No, not peace. Hang on.

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.

Leonard: I'd suggest using some lubricant, but I have a feeling you fell on that as well.
Howard: Not funny, Leonard.
Raj: Really? A robot hand’s got a death grip on your junk, dude. That’s funny, ask anyone.

Althea: What is this?
Howard: It's a robot arm.
Althea: Where's the rest of the robot?
Howard: I only built the arm.
Althea: Because that's all you needed, right?

Sheldon: I am aware of the way humans usually reproduce which is messy, unsanitary and based on living next to you for three years, involves loud and unnecessary appeals to a deity.
Penny: Oh, God.
Sheldon: Yes, exactly.