Washington - "Are you okay?" Harry asks Sally as she starts moaning across the table from him at a crowded New York deli. Billy Crystal's character doesn't know it yet, but his best friend (played by Meg Ryan) is about to win an argument in an unusual way.
"Oh God," Sally says, running her hand through her golden curls and down her neck, tossing her head back as her moans get louder. Harry puts his sandwich down, a look of defeat on his face as he realises he's about to watch his best friend prove him wrong - by demonstrating in public that, yes, women fake orgasms. Just watch and listen, buddy. You'll see how hard it is to tell if someone's pleasure is real, or manufactured for your own satisfaction.
Sally smacks her hand on the table, yelling "Yes! yes! yes!," as the other diners turn to watch. Sally caps it off with a triumphant bite of coleslaw and a smile.
The scene lasts only three minutes, but its impact has endured for decades, as the film marked its 30th anniversary last week. The scene's punchline - "I'll have what she's having,"uttered by Estelle Reiner, mother of the film's director, Rob Reiner - ranks 33rd on a list of the American Film Institute's list of the 100 greatest movie quotes of all time.
"The orgasm scene became bigger than the movie it came from," Richard Cohen, a Washington Post columnist and close friend of Ephron's, wrote in a book about their friendship.
It was the moment women realised this thing they were doing in private was, in fact, universal. It was the first time many men learned about the charade.
Not everyone understood the joke. "When the scene was shown to a Las Vegas convention of movie distributors, the men in the room did not react at all. They didn't get it," Cohen wrote. "The women, however, did. They laughed, and their laughter became infectious until, one by one, the men joined in."
It was not clear to Ephron, Cohen wrote, "whether the women had, in effect, given the men permission to laugh, or whether the men were being told that something up on the screen was funny and they had better laugh or look stupid."
Jennifer Gunter recalled a similar reaction when she saw the film as a 22-year-old medical student in Canada. The women in the theater exploded in laughter while the men were silent. "It was a really cool moment," said Gunter, an obstetrician, gynecologist and author of The Vagina Bible.
Gunter thinks the scene was incredibly validating for women - it gave more of them permission to talk about their lack of satisfaction in the bedroom. "Even if it doesn't make a woman feel that she can have a conversation with her partner," Gunter said, "just knowing that you're not the only person doing something is incredibly powerful."
Oddly enough, the film's producer's girlfriend's sister - model and actress Dani Minnick - was the one who suggested Harry and Sally discuss women faking orgasms. Ryan said Sally should act out a climax in a public place. And Crystal came up with the line "I'll have what she's having".
The scene has made an impact on young feminists who were born generations later. Lux Alptraum was six years old when the film came out and did not see it until her late 20s. Still, she knew of the scene long before she saw the movie.
Movies play such a large role in shaping our ideas about sex, Gunter said - and the Katz's scene in When Harry Met Sally, especially at the time, was the rare one that presented a particularly female perspective. But the conversation the movie started is one couples are still tripping over.