MITCH: We met in court ... I'll rephrase it. I saw you in court ... Don't you remember one of your practical jokes that resulted in the smashing of a plate-glass window?
MELANIE: I didn't break that window. What are you, a policeman?
MITCH: No, but your little prank did. The judge should have put you behind bars. I merely believe in the law, Miss Daniels. I just thought you might like to know what it's like to be on the other end of a gag. What do you think of that?
MELANIE: I think you're a louse.
MITCH: I am.
This is our first introduction to Mitch and Melanie—and they're involved in some deceptive practical joking. Hitchcock may have thought it was amusing to have his actors be characters who are pretending right from the get-go. Very meta.
ANNIE: Did you drive up from San Francisco by the coast road?
ANNIE: Nice drive.
MELANIE: It's very beautiful.
ANNIE: Is that where you met Mitch?
ANNIE: I guess that's where everyone meets Mitch.
Annie isn't lying here, but she's not telling everything. She's keeping her relationship with Mitch close to her chest, at least for now. She's also suggesting that Mitch may not be as straightforward as he seems; how many women does he meet in San Francisco, anyway? Seems like everybody in Bodega Bay is repressing something.
MITCH: You were lying!
MELANIE: Yes, I was lying.
Melanie admits she was putting Mitch on about knowing Annie. This is an important turning point; after this, Melanie doesn't really lie any more. As the focus of the film shifts from her flirtation with Mitch to the bird attacks, Melanie's personal story matters less. Do you think this makes her less interesting as a character?
MELANIE: On Mondays and Wednesdays, I work for the Traveler's Aid at the airport.
MITCH: Helping travelers?
MELANIE: No, misdirecting them. I thought you could read my character. On Tuesdays, I take a course in General Semantics at Berkeley, finding new four-letter words. That's not a job, of course, but—
Melanie is joking that her job is to misdirect travelers, but she knows that Mitch is already under the impression that she lies and misrepresents. Maybe she thinks that by acknowledging that, she can appear more genuine to him.
SEBASTIAN SHOLES: Hell, maybe we're all getting a little carried away with this. Admittedly, a few birds did act strange, but that's no reason to—
MELANIE: I keep telling you, this isn't "a few birds"! These are gulls, crows, swifts!
MRS. BUNDY: I have never known birds of different species to flock together. The very concept is unimaginable. Why, if that happened, we wouldn't stand a chance! How could we possibly hope to fight them?
Here's an example of self-deception. Mrs. Bundy, the amateur ornithologist, and Sebastian the fisherman are convincing themselves that the birds aren't really a danger because they don't want them to be a danger. Melanie, who lied about birds at the beginning of the film, is now telling the truth, but nobody wants to believe her. Oh, the irony. It's probably easier to disbelieve an outsider, which Melanie definitely is.