Sheldon: Yes, since their relationship became carnal, Penny has updated his designated term of endearment, distinguishing him from those she calls "sweetie," usually as an attempt to soften a thinly-veiled insult.
Penny: You're boring people, sweetie.
Sheldon: Although sometimes, she omits the veil entirely.

Wolowitz: Raj, I'm gonna really miss you.
Raj: Will you come visit me?
Wolowitz: 17 hours is a really long flight, how about we meet halfway?
Raj: Halfway is 600 miles off the coast of Japan
Wolowitz: We'll skype

Leonard: I've always been a little confused abut this -- why don't Hindus eat beef?
Raj: We believe cows are gods.
Sheldon: Not technically. In Hinduism cattle are thought to be like gods.
Raj: Do not tell me about my own culture Sheldon! In the mood I'm in I'll take you out, I swear to cow!

Raj: When we tell the story, let's end it differently
Wolowitz: What are you thinking? A big musical number?

Interesting. Sex works even better than chocolate to modify behavior. I wonder if anyone else has stumbled onto that

Sheldon

Sheldon: Leonard, you can't train my girlfriend like a lab rat
Leonard: Actually, it turns out I can
Sheldon: Well you shouldn't

Yes, she's pushy, and yes, he's whipped, but that's not the expression

Wolowitz [to Raj]

They're called tattoo sleeves. I bought them online. Raj got a set too. Put them on, have sex with some freaky girl with her business pierced and I can take them off and still be buried in a Jewish cemetery

Wolowitz

Penny: I give up, he's impossible
Sheldon: I can't be impossible, I exist. I believe what you meant to say is, "I give up, he's improbable."

Penny: I'll tell you what, next french toast day, I'll make you oatmeal
Sheldon: Good lord, are you still gonna be here next french toast day?

Oh man, did the KISS Army repeal "Don't Ask, Don't Tell?"

Penny [after seeing Wolowitz in his goth outfit]

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.

TBBT Quotes

Oh, Bernadette, please play my clarinet.

Raj's poem

Sheldon: I'll have a diet Coke.
Penny: Can you please order a cocktail? I need to practice mixing drinks.
Sheldon: Fine... I'll have a virgin Cuba Libre.
Penny: That's... rum and Coke without the rum.
Sheldon: Yes, and would you make it diet?