Raj: Anyway, if it's okay with you, we should talk about Howard's bachelor party.
Sheldon: Well, seems like a bit of a let down after our lichen conversation, but, what do you know, youre half swan.

Sheldon: I will form my own team and will destroy the molecular bonds that hold your matter together, and reduce the resulting particular chaos to tears.
Leonard: Thanks for the heads up.

Sheldon: I always thought if I were enslaved, it would be by an advanced species from another planet. Not some hotsie-totsie from Glendale.

Penny: Get them down!
Sheldon: Apologize.
Penny: Never.
Sheldon: Then you just get a very long stick and play panty pinata!

Sheldon: I want you to tell me that Howard is being mean to me for no reason.
Penny: Fine, Howard is being mean to you for no reason.
Sheldon: I knew it!

Sheldon: Yeah, I hate wedding receptions. I wish the bride and groom would take a cue from Bilbo Baggins. Slip on the ring, disappear and everyone goes home.

Spock Doll: What is the purpose of a toy?
Sheldon: To be played with.
Spock Doll: Therefore to not play with it would be...?
Sheldon: Illogical. Damn it, Spock, you're right.

Penny: What is the truth?
Sheldon: My Mr. Spock doll came to me in a dream and forced me to open it. And when the toy broke I switched it for yours. Later, he encouraged me to do the right thing and I defied him. And then I was attacked by a Gorn.
Leonard: Okay, that I believe.

Sheldon: I thought where you come from they don't have emotions.
Spock Doll: I come from a factory in Taiwan.

Sheldon: Everyone knows that I'm our group's resident cut-up.

Sheldon: 50% of marriages end in divorce, but 100% of sundae bars end in happiness.

Sheldon: I love astro-physics. It's like looking at the universe naked.

Leonard: Well you don't have to worry, we broke up again.
*Sheldon gives awkward look and then throws his papers in the air with one of them landing next to his head.
Sheldon: Do you ever think about other people, Leonard? Do you?

Sheldon: I'm baaaaaaaaaaaaaaaack.

Sheldon: Uh oh, hypothetical aftershock. (Sheldon grabs Leonard and pushes him over) And that's why we wear hard-hats.