"People in L.A. are obsessed with hiking," Corden told the camera. "I don't know very much about hiking, so I thought to help show me the ropes, I'd bring my friend, Mr. Chris Pratt."
The "Jurassic World" actor joined Corden for what was supposed to be a simple, 45-minute hike -- but 60 feet in, and Corden was already out of breath.
"OK, I'm blacking out," Corden said, gripping onto Pratt's shoulder. "I'm blacking out a little bit. I'm tired. It gets tough. I need to take a little sit-down. I need to take -- I need to take a knee."
"No, man. We got this," Pratt said while urging the CBS late-night host on. Turns out Corden's backpack filled with items such endless rolls of toilet paper and empty water bottles in case they had to drink their own urine didn't help him out as much as he hoped it would, but the two marched on.
During their trudge, Corden asked Pratt what body part of his he'd eat first if they ended up stuck on the trail.
"I'd just cut you open and sleep inside you if it got cold, like 'Star Wars,'" Pratt said. Corden's answer was a little different -- and way more disturbing. He said he'd eat Pratt's member, to which Pratt replied, "You're gonna need more calories than that!"
After Corden dipped plants he found into a bottle of ranch dressing he brought with him, and drank the juice of some random dog's poop (he said he saw it in a movie), he and Pratt finally made it to the top.