14/07/2014 05:03 BST | Updated 31/07/2014 06:59 BST

National Orgasm Day: How Meg Ryan Faked Orgasm In 'When Harry Met Sally', With Some Help!

To celebrate National Orgasm Day, we thought we'd dive into the annals for one of the big screen's most notorious moments, when Meg Ryan proved to Billy Crystal what he never dared for a moment to believe - that a man can never spot when a woman is faking her pleasures.

It is 25 years since Meg Ryan orchestrated an orgasm in a deli for her role in 'When Harry Met Sally' but, according to director Rob Reiner, she needed a little help getting there.

Meg starred with Billy Crystal in one of cinema's most enduring comedies, which posed the question, 'Can men and women ever really be friends?' Sally said yes, Harry said no, because sex always got in the way. He also said that no man could be fooled by a woman's exhalations... until Sally proved him wrong.

Meg Ryan made her name with this hilarious scene in 'When Harry Met Sally'... with Rob Reiner's help

The late, great Nora Ephron based her script on conversations she had with Rob Reiner about his time as a single man, while much of the dialogue was borrowed from daily chats Rob would have with his male star, Billy Crystal.

Meg Ryan got the role after other actresses, including Elizabeth Perkins and Molly Ringwald were almost cast. It made her America's sweetheart and a global star.

And the lady in the deli who famously ordered "what she's having"? That was Estelle Reiner, Rob's mother, who died in 2008, and was celebrated by the New York Times for delivering one of the best lines in cinema history.

Katz's Deli, where the scene was shot, has a sign pointing out the table where Sally and Harry sat for their intimate chat, adding, "We hope you had what she had!"

Earlier this week, Rob Reiner told HuffPostLive how he had to cajole the memorable performance out of his leading lady.

"Meg was nervous. Obviously you're in front of extras and all the crew members and everything. So the first few times we did it, she did it kind of weak. It was a little tepid," Reiner said. "I said, 'Look, let me show you what I want' after a few takes that weren't so good."

In the video below, Rob Reiner gives a taste of what his instructions looked like...