24-hours upon entering the Big Brother house, ‘Nanna’ Terri Munro is back inside thanks to a surprise challenge.

The North Richmond resident has been given the task of playing mother to 17-year-old party-boy Corey Worthington, who went into the house on Sunday night as a house guest.

Big Brother has given Terri the power to tell the infamous Corey what he can and can’t do.

Big Brother dropped the bombshell on the perplexed housemates in the closing minutes of Sunday night’s show, by explaining that as a minor, Corey required “an experienced mind” to guide him, and Big Brother could not see any suitable options in the house.

“Please welcome back Terri,” Big Brother announced moments later.

Terri’s return was welcomed by some of the housemates, while others were not so happy.

“I swear if she comes in,” Nobbi said just before the surprise was announced. “Do you know how much I’d cop it?”

Nobbi, who openly criticised the 52-year-old when she was evicted, and as a result was banished to the Combi van by Terri, let out a tirade of bad language. “That’s so stiff,” he later complained. Nicknamed ‘Nanna’ by host Kyle Sandilands, Terri had been in lock-down for a week after she was first evicted.

“Nanna’s been in storage for a week, but she’s out now and she’s back as an intruder,” Kyle said. As well as the entry of Corey and re-entry of Terri, Sunday night’s episode saw three more male housemates added to the Big Brother house, after the public voted for their top three additional housemates online.

In Monday night’s episode, Big Brother called Corey and Terri into the Diary Room, and told Terri if she completed the task of keeping young Corey under thumb, she’d be reinstated as a housemate once more.

Terri’s fate remains as precarious as that of other housemates.