The campmates are set to face a gruesome all-you-can-eat challenge on Wednesday's episode of I'm a Celebrity... Get Me Out of Here!

A new teaser trailer shared details of what is in store for contestants, as a behind-the-scenes camera caught a chef putting the finishing touches on a 'bug cake'.

It appeared to be a delicious-looking classic white sponge, but its ingredients included Surströmming, a famously foul-smelling Swedish herring dish.

'We're using tofu and mash for the icing,' explained the chef as she was seen smothering the baked cake with the mixture.

She added: 'And we're just going to top it up with some bugs and a little bit of sprinkles for that little touch, you know.'

Admitting it 'smelled bad', the chef said that flies have been 'having a party' around the cake.

The celebrities are 'definitely going to vomit,' the chef predicted, after they get a taste of the bizarre dish, and she added: 'There is so, so much food and it's all disgusting... I hope you guys are ready.'

Producers have released preview images showing Neighbours star Rebekah Elmaloglou struggling to make it through the eating challenge, which includes bull's testicles and 'brain pies'.

Meanwhile, Channel Ten has dropped another teaser for the mid-week episode, revealing that contestants will face an elimination on Wednesday.

A shocked Cyrell is seen learning the news on the bone phone and announcing it to her campmates.

'No, no, it's really bad,' she yells.

'Now I don't want to go,' a surprised Matt Zukowski says during the preview, adding: 'I feel like I really want to be here till the end.'

It comes after Deni Hines made a dramatic exit from the survival series after declaring she desperately needed to use a proper toilet due to constipation.

The singer walked out of the reality series during Tuesday's episode after complaining that the camp diet of rice and beans was 'backing her up' and she was not comfortable using the outdoor bathroom facility, known as the 'long drop'.

'I wanna go home. If our team gets rice and beans tonight, I'm going home!' the 55-year-old warned her co-stars.

When rice and beans were indeed again on the menu that evening, Deni uttered those famous words: 'I'm a celebrity...get me out of here!'

Deni then listed the litany of toilet-related reasons that she wanted to exit the jungle-based series, in addition to complaining that there were 'too many personalities' in the camp.

'I want to leave the jungle because I can't s**t. It's been six days. I can't do rice and beans again. That will plug me up again,' she said.

'I refuse - refuse - to sit on that long drop more than five minutes, and I know it's going to be more than five minutes. I want to go to a real toilet.'

Deni's departure left the campmates feeling deflated, but few tried to talk her out of leaving.

The pop star hadn't been making many friends in the South African jungle.

On Monday's episode of the popular reality series, the It's Alright hitmaker clashed with comedian Nath Valvo, almost reducing him to tears.

After taking a dig at Triple J star Concetta Caristo for not helping out around the camp, Deni then set her sights on Nath.

'You're lazy as f***,' Deni said to Nath, who was taken aback by the statement.

He replied: 'Can you not say that, Den, because I've been offering [to help out] but I get told off.'