EXCLUSIVE: Ashton Kutcher and 'That '70s Show' Co-Star Danny Masterson's Daughters Are Already Best Friends

The dads reunited on 'The Ranch' and told ET their daughters can be 'terrors' with each other.

It's been 10 years since That '70s Show went off the air and a lot has changed for Ashton Kutcher and Danny Masterson.

For example, they're both dads now: Kutcher and wife Mila Kunis have 1-year-old daughter Wyatt, while Masterson and wife Bijou Phillips have a 2-year-old girl, Fianna. And now that the co-stars are reuniting on Netflix's The Ranch, their little ones have become fast friends.

"I don't have to force them [to be friends], they just kick it," Kutcher told ET at the show's premiere on Monday. "They're terrors in the hall. We actually had to calm them down one day because they were bothering the set next door."

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Masterson had similarly adorable stories about bring your daughter to work day -- which is apparently every day.

"We bring them there every weekday," he said. "They'll run up and down, and sometimes there will be a really dramatic scene being shot, and my daughter will be at Craft service, screaming, 'I want that!' But it's been really fun having Wyatt and Fianna running around the set, and I hope that they get to grow up there the next 10 years."

A sentiment Kutcher seems to echo, as the 38-year-old actor opened up about how much his friendship with Masterson means to him.

"What's cool is from that show to this show, we've been going through, like, stages of life," he told us. "It's just awesome to be able to share that. We come to work and his daughter is a couple months older than my daughter, so we'll talk about what's going on, what they're going through and what we're going through as parents."

"It's just great to have someone to share it with," he concluded.

Plus, we found out if Kunis might ever guest star on her husband's new series. Find out what Kutcher told ET in the video below.