Entertainment TV Ashton Kutcher Jokingly Berates Laura Prepon for Keeping Her Engagement Secret: 'This Is Unacceptable!' "I shouldn't find out when I get off the plane!" Ashton Kutcher told his former That '70s Show costar Laura Prepon on Friday's Live with Kelly By Aurelie Corinthios Published on October 7, 2016 11:13 AM Share Tweet Pin Email Laura Prepon‘s engagement came as a surprise to everyone — including her longtime friend Ashton Kutcher! Just three days after the Girl on the Train star and her fiancé Ben Foster went public with their engagement at the film’s premiere in New York City, Prepon appeared on Friday’s episode of Live with Kelly — which Kutcher just so happened to be co-hosting with Kelly Ripa. Prepon, 36, came running out to give her That ’70s Show costar a huge hug. “He’s so pissed at me!” she said, laughing. “I love you, but I am so pissed you,” said Kutcher, 38. “Pre, Pre — this is unacceptable! This kind of thing is unacceptable!” “But if anyone understands the private lives … you get it!” she said. “Oh, I get it. But private lives include friends!” Kutcher insisted. “Like, I shouldn’t find out when I get off the plane!” The two bantered back and forth, affectionately calling each other “Kutch” and “Pre.” “This is deep. This is really, really deep,” said Kutcher. “The amount of crap that you gave Mila [Kunis] and I … and you and Ben Foster?! We’ve known each other all together just as long!” “It is true. We’ve known each other for like, 20 years,” acknowledged Prepon. “‘Cause we all started hanging out [when That ’70s Show started] in 1998. And every Friday after our taping all of our friends would come hang out and [Ben] was there.” Ripa then called attention to Prepon’s stunning ring — a large round solitaire on a thin pavé yellow gold band — and pointed out that solitaire diamonds are rumored to yield long-lasting marriages. As (the notoriously private) Prepon squirmed, Kutcher laughed. “I know how much you hate talking about this and it makes me happy,” he said. “I know, you’re so giddy right now!” Prepon said. As for how the happy couple celebrated? Well, Prepon didn’t give away too much. “We’re really private so we kept it kind of private, as Kutch can attest because no one really knew about it,” she said. “And then we just kind of came out with this week!” Live with Kelly airs weekdays (check local listings) and The Girl on the Train hits theaters Friday.