Jane Fonda says she had a thriller night with Michael Jackson sometime in the early 1980s.

“I saw Michael Jackson naked,” the “Grace and Frankie” star shared Monday on “Watch What Happens Live with Andy Cohen.”

Fonda played “Plead the Fifth” on the Bravo show while promoting her new film, “Book Club: The Next Chapter.” During the segment, Cohen, 54, asks his guest three questions — and they can only plead the fifth once.

After Cohen asked Fonda to name “one man in Hollywood that tried to pick you up once that you turned down,” she revealed she went skinny dipping with Jackson, who died in 2009 at the age of 50.

“Okay, I’m listening,” Cohen said as his jaw fell open. “Where’d you see him naked?”

The two-time Academy Award winner said Jackson came to visit her on “a beautiful moonlit night” at her little cottage on the lake while she shot 1981’s “On Golden Pond.”

“And you said, ‘Let’s skinny dip,'” Cohen guessed.

“No, he did!” Fonda replied.

“I think because he knew he was going to die young and I would talk about him, being naked,” she explained as the studio audience laughed. “He was skinny!”

Cohen responded, “I’m not going to ask anything else about it to be respectful of Michael.”

The Post reached out to Fonda for comment.

Fonda’s answer to Cohen’s initial question about a Hollywood man that she turned down was the French director René Clément, who died in 1996 at the age of 82.

“He wanted to go to bed with me because he said the character had to have an orgasm in the movie, and he needed to see what my orgasms were like. He said it in French, and I pretended I didn’t understand,” Fonda claimed.

“I have stories for you kid, we don’t have time,” she said to Cohen with a smile.