Rob Reiner famously cast his mother in a key scene in his 1989 classic When Harry Met Sally but he now says he may not have realized how awkward directing it was going to be.

The director appeared on CBS 60 Minutes on Sunday night, where he opened up about his newly released sequel, Spinal Tap II: The End Continues, as well as his late-80s hit starring Meg Ryan and Billy Crystal.

The latter starred Crystal and Ryan as the title characters, and the two had a key scene in the film where Sally and Harry are having lunch at a busy deli. Their conversation consists of Sally trying to convince a dubious Harry that at least one of his past sexual partners has more than likely faked an orgasm with him. Sally fakes the act loudly, while banging on her table and brings stares from fellow diners. The scene ends with one of the greatest lines in movie history, uttered by Estelle Reiner: Ill have what shes having. But things got really awkward for Reinger when he had to step in and show Ryan how he wanted her to act out the moment.

First couple of times, she didnt do it full out, he said. And finally, I sat across from Billy. And I acted it for her. And Im pounding the table, Yes! Yes! Yes! And Im realizing Im having an orgasm in front of my mother, you know? Theres my mother over there.

The movie ends with spoiler alert! longtime friends Harry and Sally getting married and talking about their wedding reception. Interestingly, that wasnt the way things might have ended: As noted on 60 Minutes, Reiner actually changed the ending to a happy one after he met his now-wife Michele, who now serves as a producer on his films, including Spinal Tap II: The End Continues.

Reiner who also reprises his role in that sequel as the director of a documentary about a hapless rock band says he realizes there was a high bar given the reviews on the cult classic original, which was released 41 years ago.

Are we crazy to do another one? he said. Its crazy. The bar is just way too high.

Christopher Guest (left) and Rob Reiner in Spinal Tap II: The End Continues. Bleecker Street / Kyle Kaplan After Harry Shearer (who plays Derek Small) successfully sued for control of the rights to the original, that paved the way to make a sequel.

Now its 40 years later, we have these rights: Whaddaya do with em? And we started throwing out ideas, Reiner explained.

Both films rely heavily on ad-libbing or schnadeling, as Reiner calls it from the cast but also from the famous faces who cameo, including Paul McCartney.

The original movie, which is credited with helping launch the mockumentary genre, poked fun at rock bands and took its inspiration from some real-life scenarios.

Apparently, Van Halen had a rider in their contract: No brown MMs,' Reiner said. So some roadie had to sit there picking out the brown MMs. Its crazy. So we looked at that, and we said, Theres a scene.' That inspired a scene wherein Nigel Tufnel (Christopher Guest) complains about the bread being too small.

Michael McKean also reprises his role as David St. Hubbins in the film, which was released in theaters last month and is also available on streaming platforms.