[Penny is trying to convince Sheldon to buy Leonard a gift]
Howard Wolowitz: Try telling him it's a non-optional social convention.
Howard Wolowitz: Just do it.
Penny: It's - it's a non-optional social convention.
Sheldon Cooper: Ah, fair enough.
Howard Wolowitz: He came with a manual.
Leonard: [why he doesn't celebrate his birthday] It's just the way I was raised. My parents focused on celebrating achievements, and being expelled from a birth canal was not considered one of them.
Leonard: How did you know my birthday's Saturday?
Penny: I did your horoscope, remember? I was going to do everybody's until Sheldon went on one of his typical psychotic rants.
Sheldon Cooper: For the record, that psychotic rant was a concise summation of the research of Bertram Forer, who, in 1948, proved conclusively through meticulously designed experiments that astrology is nothing but pseudoscientific hokum.
Penny: Blah, blah, blah, a typical Taurus.
Sheldon Cooper: The entire institution of gift giving make no sense. Let's say that I go out, and I spend 50 dollars on you, it's a laborious activity, because I have to imagine what you need, where as you know what you need. Now I could simplify things, just give you the 50 dollars directly, and you could give me 50 dollars on my birthday, and so on, until one of us dies, leaving the other one old and 50 dollars richer. And I ask, is it worth it?
Howard Wolowitz: We're in a hospital right now.
Penny: Why? Is Leonard okay?
Howard Wolowitz: Leonard's fine. I'm fine, thanks for asking, by the way.
Penny: Okay, I don't need your attitude. Listen, just hold him there a little longer.
Howard Wolowitz: Look, I've done my best, but he wants to go home and I don't know how to stop him.
Penny: Okay. How about this? You keep him there a little longer and when you get to the party, I'll point out which of my friends are easy.
[Howard remains silent, unsure what he just heard]
Howard Wolowitz: Don't toy with me, woman.
Penny: I got a hot former fat girl with no self esteem, I got a girl who punishes her father by sleeping around, and an alcoholic who's two tequila shots away from letting you wear her like a hat.
Howard Wolowitz: Thy will be done.
[Howard hangs up and pulls the peanut-filled granola bar out of his back pocket]
Howard Wolowitz: [to his groin] I'm doing this for you, little buddy.
Penny: Okay, here's the deal: you either you help me throw Leonard a birthday party, or so help me, God, I will go into your bedroom, and unbag all of your most valuable, mint-condition comic books and, on one of them, you won't know which, I'll draw a tiny little happy face in ink.
Sheldon Cooper: You can't do that! If you make a mark in a mint comic book, it's no longer mint.
Penny: Sheldon, do you understand the concept of blackmail?
Sheldon Cooper: Well, of course I... Oh... Hey, I have an idea: let's throw Leonard a kick-ass birthday party!
Howard Wolowitz: Okay, I get it. I know how the world works. How 'bout if I were to introduce you... to the man who freed your people?
Althea: [shows a five-dollar bill] Unless my people were freed by Benjamin Franklin and his five twin brothers, you are wasting your time!
Leonard: Look, I am in the "Halo" battle of my life here! There's this kid in Copenhagen; he has no immune system, so all he does is sit in his bubble and play "Halo" 24-7.
Howard Wolowitz: Can't you play him some other time?
Leonard: Not if you believe his doctors.
Leonard: I don't celebrate my birthday
Penny: Shut up. Yeah, you do.
Leonard: It's no big deal. It's the way I was raised. My parents focused on celebrating achievements and being expelled from a birth canal was not considered one of them.
Penny: That's so silly.
Sheldon: It's actually based on very sound theories. His mother published a paper on it.
Penny: Well, what was it called? "l Hate My Son and That's Why He Can't Have Cake"?
Sheldon: It was obviously effective. Leonard grew up to be an experimental physicist. Perhaps if she'd also denied him Christmas, he'd be a little better at it.
Althea: Oh, I understand, but unfortunately, this hospital is not equipped to treat stupid.
Sheldon Cooper: We might as well stop. It's a stalemate. You're beating me in "Tetris," but you have the upper strength of a Keebler elf.
Raj Koothrappali: Keebler elf? I've got your Keebler elf right here!
Raj Koothrappali: [grunts; tries to pull harder, with both hands, but Sheldon doesn't budge] Okay, it's a stalemate.
Penny: [to Leonard] This is the saddest thing I've ever heard.
Howard Wolowitz: You think?
Howard Wolowitz: [to Leonard] Go ahead - tell her about your senior prom.
Sheldon Cooper: I think a birthday party's a terrible idea. I envy Leonard for growing up without that anguish... Year after year, I had to endure wearing comical hats while being forced into the crowded, sweaty hell of bouncy castles. Not to mention being blindfolded and spun toward a grotesque tailless donkey as the other children mocked my disorientation.