With his signature honesty, the Love Island star admitted that he had barely watched any of the show before, and was going in blind.
"I never considered anything like this," Callum told 10 Play before heading to the jungle, "I remember when I was a bit younger in the UK I used to see this show, so it's a surreal feeling now to be actually on it.
"I haven't watched it for years so it's going to be relatively new for me. I just know that you've got to do challenges and get coins and stars for food but I don't know how the whole system works, who does the challenges and what they entail. It's all going to be new, but that's what's exciting! The unknown!"
Initially, Callum wasn't sure if the offer to give up the luxuries he's used to and go live in the middle of the South African jungle with a handful of celebs was a joke.
"I've never camped in my life, like I've never even thought about camping, let alone in a jungle," he admitted. "Even music festivals that require you to camp, I'd always get an apartment somewhere nearby and stay there.
"For me to be stuck in the jungle is going to be an absolute madness, yeah. I'll be shitting myself if I see a little bug or cockroach. There have been times when I've seen a spider in my room and I've gone back to my parents' house to stay there for the night.
"I can't sleep knowing there's a spider in my room."
On top of the creepy crawlies keeping him awake, Callum said one of his biggest concerns has to do with the extremely reduced portions the celebs will have to live off.
"I am very active and I eat a lot of food, like... a lot of food. For me to be limited with the amount of food I can have is going to make me a little bit more agitated as well.
"Obviously we're all in the same boat, we've just got to go with the flow," Callum continued. "There's nothing you can do other than do well at the challenges."
Having appeared in both Love Island Australia and the global spin-off Love Island Games, Callum raved about a magical snack draw that would refill throughout the day in the villa.
"It was like a conveyor belt of snacks, it was the best thing ever," he said, staring off into the distance as if remembering a lost love.
"This is the f**kin' opposite, isn't it? I've gone from having all this wide variety of snacks, juices and stuff that's brought out to me then and there, whenever I want - to literally having not what I want, and I don't know if I can even get it to begin with!"
Some celebrities are tactical with their approach in the jungle, going on a mini detox to get their bodies prepared for the reduced calorie intake and the lack of flavour, sugar, and caffeine especially.
"I'm a simple guy, I can't plan too far ahead and do strategies and stuff," Callum laughed. "That being said, if I'm that hungry, I'll do a lot for food so I think if I need to win the challenges to feed myself it's like fight or flight, I'll do a lot better in the challenges and surprise myself because I know I'll need to eat."
Speaking of challenges, Callum may be craving calories after only a few nights in camp, but he's also dreading facing any eating challenges the future may hold.
"I have the weakest stomach and a crazy gag reflex," he admitted. "Even if it smells not right I won't touch it. I can't even look at it.
"If it doesn't smell appetising I won't touch it, so I guess I'll have to just hold my nose, shut my eyes and hope for the best."
So far the eating challenges, sleeping outdoors and the lack of food are all going to be major hurdles for the Love Island favourite, but is there anything that he is excited about?
"Heights are probably going to be an issue, I'm not a crane driver, eating's going to be an issue, no food's going to be an issue, sleeping arrangement, it's not going to be a king-sized memory foam mattress. All and all, it's going to be a lot of issues," he joked.
"But, in saying that, the biggest issue for me is probably not having a mirror at my disposal! I've got no mirrors, no hairspray, no hair products. That's the main concern, innit? Do you know what I mean? No variety in my outfits, I'm in beige all day!"
Callum's sacrifices to his hairstyling are all for a good cause, as his time in the jungle is in support of Movember, which raises money and awareness for men's health issues, specifically prostate cancer, testicular cancer, and men's suicide.
"It's very close to me, I feel like a lot of people these days - especially men - are a little bit too scared to speak about their mental health. I wanted to spread awareness for men's mental health," Callum explained.
You can find out more about Movember, as well as all the charities the other celebrities are supporting here.
I'm A Celebrity... Get Me Out Of Here! continues Sunday-Thursday at 7.30 on 10 and 10 Play!
