Controversial blogger Perez re-entered the house following Patsy Kensit's eviction and the housemates learned he never 'walked' but, in fact, was watching their every move in a secret room.
With Perez's arrival, everyone was keen to know what he witnessed during his time away, and he wasted no time in filling in Nadia about Katie Hopkins.
Perez told Nadia that Katie has been speaking about Keith Chegwin behind his back, and upon hearing this, Nadia let rip at Katie in the bedroom.
"You've continued to b***h about him, that is two-faced," blasted Nadia. "There's a real problem in this house in that people don't actually understand what two-faced means. It means smiling into the face of one person and then turning and saying something really nasty into the face of someone else."
After hearing the commotion, Calum asked what has caused Nadia's outburst.
Nadia hit back: "What do you mean what is going on? She's [Katie] talking to him everyday and then b****ing behind his back. He's the nicest guy here."
Calum asked again: "Nadia, what is wrong with you? Chill man."
But Nadia said: "Don't passive aggressive with me. Shut up, don't tell me what to do. Yes shut up, shut up!"
Possibly referring to a previous incident, a shocked Calum told her to "apologise for earlier", but Nadia hit back: "I'm not apologising to you for anything."
Calum blasted: "You and Patsy should have gone together man. Shocking behaviour from both of you. Have you not seen what's happened here?"
Nadia continued to say that she will not apologise, adding that Calum has really "disappointed" her.
Before exiting the bedroom, Calum sarcastically replied: "Oh have I, mum?! Do one." Loose Women star Nadia then called Calum "two-faced", saying: "That's the real Calum".
Cheggers, meanwhile, remained silent as he sat next to Katie Price observing the chaos.
After Perez's entrance last night, he learned that viewers were voting to either curse him with eternal nomination or grant him a guaranteed pass to the finale. The public chose the curse.
Watch Nadia and Calum's argument here.
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