And it had viewers raging.
However, the radio host, who fears heights, also won a full house 100ft above ground in 'Space Your Fears'.
Yesterday, the campmates were instructed to choose a player for the next Bushtucker Trial, entitled 'Tutankha-doom'.
Having not faced one in over a week, Iain volunteered to take part - until Dennis made his opinions clear.
"My only problem, I’ll be honest with you Iain, is you’ve said 'Get Me Out Of Here' twice," he admitted. "What I don’t want to do is have no dinner."
"Okay, but I also got eleven stars on one," Iain reminded him.
"I get that, but you’ve said 'Get Me Out Of Here' twice out of the three you’ve done," replied Dennis, seemingly forgetting that Iain also beat Kezia Dugdale to win the camp divide Trial.
Iain pointed out that one of his failures was a less crucial challenge, but Dennis continued: "If you come back with nothing, everyone will be upset."
The footballer's persistence led Iain to snap. "I get it, you don’t want me to do it. I withdraw my offer," he said.
"Does that mean I can do no Trials for the rest of the run then? Because that feels a little unfair."
Despite having "a slight issue" with Iain's track record, Dennis responded: "You don’t need to be like that."
Iain shared his frustrations in the Bush Telegraph. "I feel significantly more confident than I did the other day, so I was quite happy to stand my ground," he explained.
"It did feel a bit humiliating having my list of failures kind of recited back to me."
However, Dennis defended his viewpoint. "People need to eat and people are hungry," he said. "If he doesn’t like my opinion, he doesn’t like it, but I have to say what I feel."
Georgia 'Toff' Toffolo also shared her observations on the clash, comparing Iain's situation to her own.
She mused: "If we’d had this mindset the whole way through, I think the boys would have said 'don’t put Toff forward'. I’ve been able to show I am strong and tough."
Watching last night, viewers were quick to chime in with their views and it was clear most felt Dennis was in the wrong.
"Dennis Wise and his little clique Amir and Jamie can do one now. I'm so over their bullying Iain and bum licking each other #ImACelebrity," one fan wrote.
"Dennis Wise is actually an awful man hope he gets voted out tonight 🙄 #ImACelebrity" another said.
And a third quipped: "Dennis Wise you ended up playing for Millwall don't talk to anyone about failures #ImACelebrity"
Back in camp, eventually, the two men cleared the air and apologised to each other.
"I have so much respect for that man, which is why it was a shock, but we shook hands and made up," said Iain.
"Hopefully that will make him go out and push himself to prove me wrong," added Dennis. "Nothing would please me more for him to come back with loads of stars."
Iain has spoke of feeling isolated by his I'm A Celebrity… Get Me Out Of Here campmates following 'Strawberry-gate', leading to criticism from viewers.