In scenes aired on last night's episode, Katie P chose to save already-nominated housemate Katie Hopkins from eviction and instead nominate Calum.
It was part of a secret task she'd been set by Big Brother.
Afterwards, she wanted to make sure Calum knew she hadn't nominated him because she didn't like him, rather because she knew he was a safe bet to stay.
"I thought I would make it equal: two men and two women up for eviction," she explained. "And I knew you would be safe. It's a compliment."
Katie P also revealed she'd nearly chosen Patsy Kensit instead as she knew how much Patsy wanted to see her children.
In the end, the ex-glamour model said whoever she chose, there would be somebody upset, adding: "The good news is everyone has another four days here anyway. Just to go through it again! F**king hell!"
Calum, however, wasn't upset by his nomination, telling Katie he understood that it was a game and she had to pick someone.
"I'm good. I'm at ease. I feel cool, calm and collected. It's no problem. It's all good, my friend. I'm all good!"
He also said: "Friday is two weeks down and I said I'd be ready to go after two anyway."
Calum faces eviction against Nadia Sawalha, Perez Hilton and Alicia Douvall on Friday night's live show.
The housemates had previously nominated Nadia, Katie H, Perez and Alicia for eviction on Tuesday night's show, but Big Brother cancelled that eviction due to Alexander O'Neal's departure.
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