Mission Survive Dame Kelly Holmes star has confessed that she was shocked by just what the show involved.
Survival Bear Grylls is leading a troupe of eight celebs in a jungle expedition across South America that has been described as 'I'm A Celebrity on steroids'.
One of the stars is Olympian Kelly who admitted she was surprised just what they had to do for TV.
She said this week: "As much as you see things that they do you're like, 'They're not going to give us this'. It was when they told us we had to wee in our bottles and I was like, 'Oh my God, do not even go there'.
"And then they came back the next day – 'Right, those wees you did in bottles, you're going to drink them!' What?! You're just thinking, 'Vomit'. Because it's a challenge you end up doing it, but it was the thought of it going down you and then the thought that you'd drunk it."
Kelly revealed: "Afterwards, everyone was retching. Ugh, just for ages and ages and ages, all you could think about was that you'd literally just drunk your own wee. It was disgusting, oh my God."
So asked just why she signed up in the first place, Kelly said: "I think it was a personal challenge."
She explained to DigitalSpy: "After athletics, I hadn't really done anything that's been a personal challenge as such.
"I've done some really great things but a lot of them have been for other people, with other people, as opposed to me going, 'Right, I want to push myself and get myself out of my comfort zone and experience something new again', and that's why I took part."
Mission Survive continues Friday at 9PM on ITV.