Greg James picked up a piece of frozen human poo after mistaking it for a microphone.
The Radio 1 DJ endured an "horrific" moment on his Sport Relief challenge when he lent down to scoop up what he thought was a forgotten piece of camera equipment, only to realise the item in question was a chilled piece of poop.
He said: "I thought someone had left the microphone on the floor and I was like, "Oh guys, you've forgotten some kit"... and it was a frozen bit of human waste... That happened. It was horrific."
Greg raised more than £1 million for charity after scaling mountains Snowdon, Scafell Pike and Ben Nevis but had to endure horrific conditions, including the Beast from the East snow storm, and he is yet to fully recover.
He said: "I still have flashbacks to being up the mountain. My hamstrings are still really, really injured. But it was an amazing thing to be part of, I feel quite proud of the whole thing. I will never do it again.
"I just think it was the perfect story. We played the whole thing out on Radio 1 over a week. We had no idea what was going to happen. The weather intervened, it was the "Beast from the East".
"Suddenly it turned into this ridiculous story that nobody was expecting.
"I don't think you can necessarily better anything like that. I think leave that as it was but continue on.
"We've made the splash now and gone, "Right an idiot was doing some stuff, let's talk about the real issue behind it", which was getting our listeners to open up about their brains."
Greg opened up about his mental health struggles after being forced to postpone the challenge midway through due to the terrible weather conditions.
Speaking on upcoming new ITV show "Zoe Ball on Saturday", he added: "People were just reaching out and saying, because of what Grimmy [Radio 1 Breakfast host Nick Grimshaw] was saying, I've gone to find help, or spoken to my mum about it or I'm finding a therapist.
"That was the real triumph of the whole thing, that's why I don't want to do the physical bit of it again."
"Zoe Ball on Saturday" airs Saturday (14.04.18) from 8.30am on ITV, and "Zoe Ball on Sunday" airs Sunday (15.04.18) at 8.30am, featuring The Saturdays" Mollie King meeting Hollywood stars Luke Evans and Dakota Fanning.