British survivalist Bear Grylls is teaming up with Tiffany Haddish for the latest episode of Bear Grylls is Running Wild.

While hiking through the desert in the greater Utah area, nature truly takes over as Haddish bluntly reveals that she’s on her period. A Running Wild first? “Probably not,” Grylls told DECIDER. But he also said it was certainly the first time someone “[articulated] it so much.”

Haddish, an A-list actress and comedian, first makes her confession after a successful 127 Hours–esque rock climb. As Grylls pulls her up to the top of the mountain, she huffs, “There are clots coming out.” Confused, he asks her to clarify “what’s coming out,” to which she bites back, “The lining of my uterus.”

“I’m gonna be honest with you. I probably picked the wrong time of the month to do this show,” Haddish admits to the cameras. “But I’m doing it.”

When Grylls stopped by DECIDER’s studio earlier this month, he praised Haddish for pushing through their rugged 48 hours together along the Colorado River in spite of the condition she was in.

“It speaks to her spirit and character,” he said. “There’s a lot of people who would go, ‘I just can’t do it at the moment.’ I think there are a lot of emotions with it, and I just really admire her tenacity. Like, ‘Not everything’s perfect, but I’m still here, and I’m all in. I’m not feeling great, but I’m all in.’”

Grylls added that he “admired” the way Haddish handled herself in the less-than-perfect circumstances. “It’s a sign of character to dig deep and do the difficult and still be in when you’re not feeling great,” he continued. “But she’s very fun as well. She didn’t shy away from that. There were endless gags around that. But she’s a fighter and a champion, and she should be really proud of herself.”

Grylls further described the Girls Trip star as a “livewire,” recalling that they “never stopped laughing.” He even thought she might’ve been a bit “nervous,” and was using humor as her coping mechanism, which wouldn’t be the first time she’s had to do that in her lifetime.

During one of their more emotional conversations in the episode, Haddish opens up about her heartbreaking upbringing in the foster care system, and how she had to use her positive attitude to deal with being bounced around to different homes.

“She was incredibly honest. I mean, she talked about some stuff she’s never talked about publicly before — some really, really, very intimate, difficult, painful experiences she went through when she was younger,” Grylls said. “I really admire that vulnerability. It’s what the outdoors does. I always think the wild never judges. You can sit together and share these moments. And, for me, it’s a privilege to be beside people in those vulnerable times.”

Bear Grylls is Running Wild airs Tuesday nights at 9/8c on FOX. New episodes are available to stream the next day on Hulu.