Jane Fonda was ‘totally down’ to make out with this co-star

Their on-screen smooch’s first take was fake.

Jane Fonda had a kissing scene with Richard Roundtree in the comedy “Moving On,” released March 17. 

Although the octogenarian co-stars were happy to lock lips, and eventually did, there were complications at first.

“The funny thing was that when that makeout scene came up in the movie, when it was supposed to shoot, Jane had a really bad cold,” the film’s writer and director Paul Weitz told The Post.

“So we actually faked it. They did everything but kiss.”

In the comedy, Fonda, 85, and “Shaft” actor Roundtree, 80, play ex-spouses who reunite at a friend’s funeral.

“She was totally down for making out with Richard,” said Weitz, 57.

“We sort of recreated that just for the close-up, of the two of them kissing … on set later.

“So Richard came in one day just to kiss Jane Fonda.”

Weitz, a Big Apple native who grew up in Carnegie House, a luxury building on 57th Street and Sixth Avenue, said Lily Tomlin, who stars as Fonda’s college friend, asked him to write the movie for the pair.

“She called me from the set of ‘Grace and Frankie’ one day, and she said, ‘I’m with Jane Fonda, just talking, and we think you should write us a movie,’” he explained.

He said working with the duo, who are friends in real life, was amusing, especially when they took jabs at each other.

“At some point where Lily was giving a dramatic pause to something, Jane thought she’d forgotten her lines, so she reminded her,” he explained. “And Lily said, ‘I’m acting here!’”

This project marks Weitz’s 13th time in the director’s chair. His directorial debut “American Pie,” which he worked on with his brother Chris, was not expected to perform well at the box office.

“I didn’t know this at the time, but when the studio was watching the dailies, they’re like, ‘This is going to be a bomb,’” he said.

The teen comedy went on to gross over $235 million worldwide and spawn three films and a spinoff series of five direct-to-video movies.

“It was a shocker,” he said. “It was really weird to go up to the theater on the first weekend and see a line around the block.”

Weitz’s three children, ages 19, 16 and 12, not only preview his movies before they are released, but provide feedback.

“They give me notes. My 16-year-old, I showed him ‘American Pie’ … that was the only movie where afterwards he said, ‘I’m proud of you, dad.’”