One could argue, and many have, that When Harry Met Sally… is the quintessential modern-day romantic comedy; a film that has, for better or worse, reverberated in each and every romcom since.

The premise is simple enough: Directed by Rob Reiner and written by the late Nora Ephron, it opens in 1977 with two college grads—Harry (Billy Crystal) and Sally (Meg Ryan)—sharing a long drive to New York City. On the surface, they couldn’t be more different, and engage in a long argument about the nature of relationships between men and women. “Men and women can’t be friends because the sex part always gets in the way,” claims Harry. A decade later, the two meet again in the Big Apple and pick up where they left off. Their nightly chats eventually blossom into a romance, and the two find themselves struggling to come to grips with the complicated feelings they share for one another.

“When it comes to When Harry Met Sally…, somebody told me they had a survey for New Yorkers to pick a movie and they screened it in all five boroughs!” exclaims Reiner. “That’s really cool.”

Indeed, just a few weeks ago, New York City screened the film in all five boroughs to commemorate its 25th anniversary (really, July 14).

In honor of the film’s 25th, The Daily Beast spoke with Reiner about the making of When Harry Met Sally… and how the movie’s iconic scenes came to be.

It’s the 25th anniversary of When Harry Met Sally... A lot of it came from the brilliant mind of Nora Ephron, but how did the idea for the film come together? The characters seem a lot like you and Nora.

Well, they are. The whole idea for the film came out of me being married for 10 years and then single for 10 years, and during the time I was single, I would be in and out of relationships, and making a complete and utter mess of my personal life. I said, “I’ve got to make a movie about how you get with a woman. Is sex always a part of the equation? If it is, can you still be friends? Can you be friends without sex?” I was so confused by the whole thing and I started talking with Nora about this idea, and she said, “Oh, let’s try and see if we can do it!” Initially, it was called Scenes From A Friendship. We didn’t know where these characters were going to go, it was just these two people that would run into each other and would be friends, and ultimately sex would become part of the equation. We interviewed each other and Billy played an extension of me, and Meg played an extension of Nora. Absolutely.

How did you arrive at Billy Crystal and Meg Ryan for the roles of Harry and Sally? They weren’t really big-name stars at the time.

I’m not telling anything Billy doesn’t know, but Billy was not a movie star at that point, and Meg, people didn’t even know. She had done something like D.O.A. and had a small part in Top Gun. Billy was my best friend at the time, so I thought he would be good in this part and I didn’t have to worry about the studio because I was the studio—we were financing our own film. It was a tricky thing because he was my best friend, so I had to be sure he was right for it because if it didn’t work, it could get really uncomfortable and awkward. But I crossed that bridge and we agreed to do it, and then we held auditions and Meg read with Billy. They had instant chemistry and I thought, “OK, this is great.”

Was there anyone else you thought of for the roles of Harry and Sally besides Billy Crystal and Meg Ryan?

I talked to Albert Brooks about it. I talked to Tom Hanks about it. I talked to Richard Dreyfuss and Michael Keaton about it. The Meg role… We saw Molly Ringwald, but I can’t remember how many people we saw there. But Meg and Billy hit it off right away.

The iconic scene will always be the fake orgasm one at Katz’s Deli—featuring a cameo by your mother as the customer who says, “I’ll have what she’s having.”

I’m so thrilled! At Katz’s now they have the sign and you can sit at that table, and from what I understand, people sit down at that table and act the scene out. And I saw this thing on YouTube that I got a big kick out of: they had a flash mob and all the women in the place were faking orgasms. And now my mother is up there as the person who delivered one of the top five movie lines in AFI history or something. You have Clark Gable and Estelle Reiner on the same list.

How did that scene come together?

Well, we were working hard on that scene and knew we had a good scene. Billy actually came up with the line, “I’ll have what she’s having.” I figured I needed an older Jewish woman to play the customer at the deli who says it, and I told my mother, “You know, this scene is going to be pretty funny and the line you have is hopefully going to be the topper. But if it isn’t, and it’s not as good as the lines she’s delivering, I may have to cut it.” And she said, “Oh, it’s OK! I just like spending the day with you.” So, she came down to Katz’s Deli, had a hot dog, and the rest was history.

How many takes did it get for Meg to nail the fake O?

She did two or three, and she did it kind of weakly. It was very tepid. I think she was nervous about having to do it in front of the cast, crew, and everybody. And finally, I said, “Here, Meg—this is what I’m looking for.” And I sat down opposite Billy and I acted it out! I pounded the table again and again going, “Yes! Yes! Yes!” and when we were done, I turned to Billy and said, “Uh-oh… I just realized I had a huge orgasm in front of my mother!” Billy jokes about it now, saying it was like being on a date with Sebastian Cabot. And then Meg sat down and did it, and she did it way better than anyone could have done.

Do you have any favorite memories from the making of the film?

Well, the best memory I have is I met my wife while I was making that movie. And what’s weird is that, in the initial ending, they didn’t get together. It wasn’t until I met Michelle that I thought, “OK, that’s how it could work for me,” and I changed the ending to where they got together. In the original ending, they drifted apart and then ran into each other one day on the street years later and chatted about where their lives went, they walked away, and the camera pulled up. It would not have been as satisfying, I think.