The Big Bang Theory Season 1 Episode 16

Sheldon: By the way, a six-year-old can hack your computer system.
Penny: (pushing him) Keep walking.
Sheldon: 1234 is not a secure password!

Sheldon: (to an electronics customer) What computer do you have? And please don't say 'a white one.'

(Howard feigns an allergic reaction to peanuts)
Howard: We have to go to the hospital!
Leonard: Now?
Howard: No, we'll wait until my tongue swells up to the size of a BRISKET!

Penny: (on Leonard's parents not considering his birthday as an "achievement" to be celebrated) That's so silly.
Sheldon: It's actually based on very sound theories; his mother published a paper on it.
Penny: What was it called, "I Hate My Son and That's Why He Can't Have Cake"?
Sheldon: It was obviously very effective. Leonard grew up to become an experimental physicist. Perhaps if she also denied him Christmas, he'd be a little better at it.

Penny: (on phone) 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: (long pause) 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: Thy will be done.

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: 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, a typical Taurus.

Leonard: I don't celebrate my birthday.
Penny: Shut up. Yeah, you do.
Leonard: It's no big deal. 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.

Penny: Well, Sheldon you are his friend. Friends give each other presents.
Sheldon: I accept your premise; I reject your conclusion.
Wolowitz: (quietly to Penny) Try telling him it's a non-optional social convention.
Penny: What?
Wolowitz: Just do it.
Penny: It's a non-optional social convention.
Sheldon: Ahh, fair enough.
Wolowitz: He came with a manual.

Sheldon: Leonard made it very clear, he doesn't want a party.
Wolowitz: Did someone say party?
Penny: He just doesn't know he wants one because he never had one.
Wolowitz: I suppose that's possible, but for the record I've never had a threesome and yet I still know I want one.
Penny: Howard here's a difference: the possibility exists that Leonard could have a birthday party before hell freezes over.
Wolowitz: Fine, if I do have a threesome you can't be part of it. (waits a minute) I'm just kidding. Yes, you can. Can you bring a friend?