Kristen Bell Talks Her and Dax Shepard's Close Relationship With Ashton Kutcher and Mila Kunis (Exclusive)

The actress spoke with ET at the premiere of her new documentary, 'Pandas,' on Saturday, and dished on her kids' love of nature shows and her husband's new podcast.

Kristen Bell has nothing but love for her and husband Dax Shepard's close friends --and fellow celeb couple -- Mila Kunis and Ashton Kutcher.

The Good Place actress walked the red carpet at the premiere of the new nature documentary Pandas, which she narrates, and Bell stopped to talk with ET's Nischelle Turner about the recent news that Shepard is joining the upcoming season of Kutcher's Netlfix sitcom The Ranch, and how the two actors became close friends.

While Bell and Kunis have starred alongside one another in several comedies in recent years, the 37-year-old actress said that it was really Shepard and Kutcher who kicked off the tradition of the couples' close working relationship.

"Really they started that with Punk'd," Bell said, referring to Kutcher's infamous hidden camera prank show that premiered on MTV in 2003, which also featured Shepard as a participant in several of the show's elaborate practical jokes.

"They fell in love and they remained friends, and I was just lucky enough to work with Mila on [Forgetting Sarah Marshall]. We became great friends and that contributed to Bad Moms," Bell said. "But yes, we love [each other]. It's a very nice foursome, and we have kids the same age. They're good people."

Bell and Shepard share two daughters -- Lincoln, 4, and Delta, 3 -- and while they didn't come with their mom to the premiere of Pandas, Bell said they are absolutely in love with nature shows and conservation.

"We watch a lot of nature shows. They love David Attenborough. We let them watch some cartoons on the weekends but mostly we sit down and watch nature shows together and talk about the animals," Bell shared. "They always want us to freeze frame the animals and take pictures on our phone and then put it next to them so they can draw it. It's kind of great."

While Bell is celebrating the release of Pandas, her husband is also enjoying some growing success with his new podcast, Armchair Expert, in which Shepard sits down with celebrities and they just talk about their life story.

The podcast, which launched in February, featured Bell sitting down as Shepard's first guest for an eye-opening discussion about their lives and their marriage. The podcast also made headlines last week for an emotional and revealing interview with Ellen DeGeneres.

"It makes me, as his wife, so excited because he's never in a better lane than when he's talking to people," Bell shared. "He likes to talk about vulnerable issues, he has a sense of intimacy when he talks to you and I'm like, 'Of course! A podcast! That's what you should be doing!' Not that he shouldn't be performing, but he's exponentially [more] happy when he's talking to people."

While the podcast has been picking up a lot of steam, it doesn't seem like Shepard plans on taking a break from acting anytime soon. It was just announced that he would be guest starring on The Ranch in a story arc lasting the second half of the show's upcoming third season.

Meanwhile, Bell's documentary, Pandas, hits theaters April 6.