Housemates will be called to stand on boxes in the garden, with each box including a potential prize, including a 50" LED TV, a mountain bike, £1,000 cash and a toilet brush.
However, the only person who will win a prize will be the housemate who stays on their box the longest.
The prizes will be listed for the housemates on a board in the garden, but no-one will know what their box contains.
In a twist, one housemate will be called to the Diary Room to allocate the prizes prior to the beginning of the task.
When housemates decide that they can no longer stand on the box, they must say their name followed by 'is no longer present', before they are allowed to see what they could have won.
Big Brother is shown daily on Channel 5 at 9pm.
Photo gallery - Big Brother Day 51:
Copyright: Channel 5