Leonard: Ready when you are, Professor Hawking.
Stephen Hawking: And a one, and a two.
All: Happy birthday to you. Happy birthday to you. Happy birthday, dear Sheldon. Happy birthday to you. (to you.)

Amy: We've got someone who couldn't be here but really wanted to wish you a happy birthday.
Stephen Hawking: Hello, Sheldon.
Sheldon: (gasps) Professor Hawking.
Stephen Hawking: Happy birthday to you.
Sheldon: Thank you so much. I can't believe you're-
Stephen Hawking: Happy birthday to you.
Sheldon: Oh, you're singing. Well, I'm sorry.
Stephen Hawking: Happy birthday, dear Sheldon.
Leonard: Uh, Professor Hawking, if you just give us one second, we'll light the candles, and we can all sing together.
Stephen Hawking: I was crushing it, but all right.

Sheldon: Thank you. That was wonderful.
Penny: Oh, wait, wait, wait. Stuart didn't get to speak.
Stuart: Oh, oh, okay. Um. Uh, Sheldon, I've spent most of my life feeling invisible, but having you and everyone-
Amy: Hey, everybody, listen up.
Penny: (To Stuart) You nailed it.

Leonard: Sheldon, we've been together so long, it's hard to remember a time you weren't in my life. And believe me, I try.
You make me laugh.
You make me a better scientist.
You make me crazy.
You're more than just my roommate, you're my brother.
Sheldon: Thank you.
Leonard: Happy birthday, buddy.

Bernadette: I can't think of anything to say that hasn't already been said. So, here's to you, Sheldon.
Raj: Hear, hear.
Sheldon: Thank you, Bernadette. That was perfect.
Howard: What? You gotta be kidding me?

Adam West: Happy birthday, young man. And if any of you have enjoyed seeing me here today, I'm also available for Comic-Cons, bachelor parties, bar mitzvahs...

Leslie Winkle: Uh, in the past, I would've said something obnoxious, like, "Happy birthday, dumbass". But I'm not gonna do it. You and I have both grown a lot, and it's just so nice to see you all again. So happy birthday, Sheldon.
Sheldon: Oh. Oh, now, you know I hate change. Say it.
Leslie Winkle: Happy birthday, dumbass!

Raj: And it was Gandhi who said, "Live as if you were to die tomorrow. œLearn as if you were to live forever."
Sheldon: And it was Sheldon Cooper who said "Let's speed this up. A lot of people want to talk."

Barry Kripke: Someone call Animal Control. There's a cougar on the loose.
Beverly Hofstadter: Barry, stop.
Leonard: Seriously, Barry, stop.

Beverly Hofstadter: Sheldon, I know the future holds great things for you, and we all can't wait to see what they are. Happy birthday, dear.

Sheldon: Wil Wheaton, go.
Wil Wheaton: Sheldon, I know that we've had our ups and downs, but I can honestly say that my life is so much more interesting because you are in it. We may have met because you are a fan of Star Trek. But I have become a fan of Sheldon Cooper. Live long and prosper, buddy. And happy birthday.
Sheldon: That's how you do it, Wolowitz. Now you see why he's famous and you're not.

Leonard: Okay, I'd better go in there and talk to him.
Amy: Well, don't you think I'm the one who should go in?
Leonard: No offense, but I've known the guy a really long time.
Amy: Well, I've, you know, seen him without pants on.
Leonard: Again, no offense, but so have I.
Amy: Well, he's seen me without pants on.
Leonard: Again, -
Penny: Okay, this is ridiculous.

(After Sheldon runs out of his party)
Adam West: I still get paid, don't I?

Howard: Sheldon, I don't think everyone-
Sheldon: Wolowitz, perfect. Everyone listen to Wolowitz.
Howard: Okay, then, uh, Sheldon, we've known each other a long time. And it is a pleasure to work with you and call you my friend.
Sheldon: Little generic. Keep thinking. We'll circle back.

Penny: Sheldon, can I come in?
Sheldon: How do you know I'm not using the facilities?
Penny: Because you e-mail me your bathroom schedule once a week, even though I've clicked unsubscribe, like, a thousand times.