Well, this is interesting!

In a candid new interview, Shirley MacLaine said sleeping with other people is the "basis for a long-lasting marriage" — including her past, 28-year union with husband Steve Parker!

"I think that's the basis for a long-lasting marriage, if you really want to do such a thing," the 81-year-old actress said of her open marriage with Steve during a recent Sirius XM Town Hall interview with Jess Cagle.

shirley maclaine steve parker getty images

Steve and Shirley in April 1964.

"I would say better to stay friends… we don't have enough time to talk about the sexuality of [it] all. I was very open about all of that and so was he," Shirley continued. "I guess you would say [we] 'practiced an open marriage' in 1954, which was another lifetime."

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"No one understood it. We did. He lived in Japan, basically. I lived in America, working, and this and that. We'd meet up, always great friends, traveled sometimes together," she added.

Shirley and Steve were previously married from 1954 until 1982. They have one child, daughter Sachi Parker, 59, together.