Jane Fonda said she was "shocked" at audience reaction to line in new film "Moving On"

Longtime friends Jane Fonda and Lily Tomlin co-star in a new film about two women seeking revenge on the husband of their late best friend. 

Fonda said she was "shocked" at the audience's reaction to one of her key lines in the dark comedy "Moving On." The line is: "I'm gonna kill you. ... I'm gonna do it this weekend." 

"I saw the movie with an audience, and they laughed," Fonda said. "I was shocked. I thought I'd failed."

But Tomlin said she knew Fonda's delivery of the line was funny — and praised her co-star. 

"When you play it straight, really heavy, it makes it ... much funnier," Tomlin said to Fonda Friday on the set of "CBS Mornings." "You're arrogant in it. You're everything. It's amazing." 

Fonda and Tomlin first worked together in the classic 1980 movie "9 to 5." They've been close friends ever since and have collaborated on many projects including the popular TV series "Grace and Frankie," which ended last year after seven seasons.

Fonda said she knew more than 40 years ago that she wanted to work with Tomlin after seeing her perform a one-woman show. 

"That was it. I was in love. I mean, I just, I've never seen anything like it," Fonda said about Tomlin's performance. "She became so many different people, and just became them profoundly."

When it came to making "9 to 5," Fonda said, "I just thought, 'Well, I'm not going to make a movie about secretaries unless she's in it. I don't want to ever do anything without her.' I just was smitten."

After decades of parallel thriving careers, Tomlin said she called the director of "Moving On," Paul Weitz, and asked him to write something specifically for her and Fonda. 

"It's just so natural and easy" for the two to work together, Tomlin said. "And people say we have chemistry. We don't know why or how, but it all works for us."

"Moving On" will be released in theaters on March 17.