Ashton Kutcher is upset and "pissed" at his That '70s Show co-star Laura Prepon. Kutcher, who recently co-hosted ABC's show Live! with Kelly Ripa, spoke about Prepon's recent engagement to Ben Foster.

Kutcher told the host [via E! Online], "I'm very upset with her right now. She just announced this engagement, and I had to find out in the news! She's my friend. It's weird like that. By the way, it's not just a random engagement. It's an engagement to another friend of mine! So, now I'm double upset that neither of them told me. I got off the plane in New York like, 'What?'"

However, the Two And A Half Men actor admitted that he kept his engagement to Mila Kunis a secret from The Orange Is The New Black star. He explained, "When Mila and I got engaged, Pre was like, 'What? This is crazy! You guys, it was like 20 years ago. You were friends and no one saw this coming, and now you're engaged and I have to find out this way.'"

"They were friends 20 years ago! They're all my friends, and everybody's hooking up, and it's weird!" he added.

Prepon, who was also a guest on the show, later explained why she kept the news a secret. After the actors hugged, Kutcher told Prepon, "I am so pissed at you!"and said it was "unacceptable" for her to keep Foster's proposal under wraps. Following which, she explained, "But if anyone understands [a need for privacy], you get it."

Kutcher replied, "Oh, I get it. But 'private lives' includes friends!" The actor then called out Prepon for "the amount of crap" she gave him and Kunis for getting together. "You and Ben Foster?! We've known each other all together just as long!" he said.

The Girl On The Train actress admitted they knew each other for 20 years. "It is true. We've known each other for, what, 20 years, right? Because we all started hanging out in 1998. Every Friday after our taping, all of our friends would come hang out or whatever, and [Foster] was there."