A newly-released clip shows Holly Willoughby, 36, wriggling around trying to get a good grip on the curtain before yanking it down when given the go-ahead by host Keith Lemon.
Keith recently dished the dirt on the cheeky new game that involves all the presenters - including Fearne Cotton - as the ITV2 show made a comeback for a brand new series.
Speaking to The Mirror Online, Keith, also known as Leigh Francis, confessed: "We have a new game where you have to rip a shower curtain out of a shower using only your bum cheeks and Holly was extremely good at it.
"But she cheated, because she said she was going for a wee, but she didn't."
ITVHolly Willoughby ripped down a shower curtain with her bare bum cheeks on Celebrity Juice
ITVHolly took part in the X-rated game during tonight's instalment of the ITV2 show
She changed her knickers to a thong so she could get a good grip on the shower curtain
The writer-producer went on to explain exactly how the blonde managed the ingenious feat, saying: "She changed her knickers to a thong so she could get a good grip on the shower curtain.
"She doesn't know I know this but the make-up ladies told me, she was practicing in her room, just so she could drag a shower curtain off!"
Meanwhile, along with her derrière, Holly's "Willoughboobies" have been the talk of chat shows this week.
During a hilarious skit on today's This Morning, Paddy McGuinness appeared behind one of the studio's cameras with Keith and cheekily zoomed in on Holly's chest.
ITVHolly regularly takes part in Keith Lemon's saucy antics
ITVThe funny game will air on the new series of Celebrity Juice
Thank you to the gorgeous @itvlorraine for having me to talk all things #trulyscrumptiousbaby with a little shower curtain up the bum thrown in for good measure! ������������
A post shared by Holly Willoughby (@hollywilloughby) on Sep 12, 2017 at 1:55am PDT
As the 36-year-old's co-host Phillip Schofield, 55, burst into laughter, Holly joked: "First time that camera's been in focus actually.”
Phillip could then be heard screeching in the background, while Paddy asked: “What? I’m just getting used to it.”
The TV personality also suffered some embarrassment on Lorraine Kelly's chat show, when the Scottish host reminded her that her bosom was still impressive.
She looked down at her chest and said: “I think they’re still there Lorraine," to which the interviewer added: "Absolutely, they are gorgeous. They’re amazing."
Celebrity Juice airs tonight at 10pm on ITV2.