One housemate will be allowed a phone call to a loved one after tonight's task.
The five survivors will be tested on how much they know about each other.
The number of correct answers will decide how much time the winner can spend on the phone.
The result will also dictate how much money they have to spend on provisions this week.
The housemates will be called to the diary room in turn and asked a question about one of their fellow contestants.
After three questions each, they must decide among themselves who they feel most deserves a phone call to a family member or friend.
Each correct answer earns the group £20 (€31) to spend on shopping and an extra five seconds of phone time.
The task will be shown live on Channel 4 at 10pm.