Viewers saw her passionately kiss the reality star on Friday, before she later got into bed with him for a 'five-minute cuddle'.
But Sarah Harding's steamy antics with Chad Johnson are exposed on Sunday's Celebrity Big Brother, thanks to a prank pulled off by Sam Thompson.
The Made In Chelsea star, 24, teased the Girls Aloud star by pretending he had seen their rendezvous while getting a glass of water - leading the singer, 35, to erupt into giggles, and admit their smooch was a 'one-off'.
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Awkward: Sarah Harding's kiss with Chad Johnson are exposed on Sunday's Celebrity Big Brother, thanks to a prank pulled off by Sam Thompson
Caught in the act: The Made In Chelsea star, 24, pretended he had seen their kiss (above) while getting a glass of water - leading the singer, 35, to admit it was a 'one-off'
On Saturday, scenes aired of Sarah and Chad, 29, indulging in a passionate lip-lock in the kitchen - believing they were away from cameras.
While they went unnoticed by their fellow housemates, Sam begins to grow suspicious of the pair, and decides to call her bluff.
He is seen telling Sarah teasingly: 'I saw...,' at which she first denies the clinch, stating: 'Oh f*** off, you didn't see anything.I don't know what you're talking about.'
Tease: Sam teases Sarah by claiming he 'saw' her kiss Chad, tricking the singer into admitting their tryst
Further pressing with his investigation, the blonde then claims he got up to get a glass of water from the kitchen, where their steamy kiss took place.
With her face falling at the thought of being caught, Sarah then admits coyly: 'It was a one-off... emotions were very high.'
As the fellow housemates begin to clock what has happened, Sarah continues, shaking her head:'It's nothing like that. It was nothing that extreme.'
Couldn't help herself: With her face falling at the thought of being caught, Sarah then admits coyly: 'It was a one-off... emotions were very high'
Wanting the full low-down, Gogglebox's Sandi Bogle then asks: 'You were kissing?', to which Sarah simply erupted into giggles, giving the game away.
Having been tricked into revealing the truth, sneaky Sam then bursts into hysterics as he shrieks: 'I knew it! I didn't even see anything!'
The reality star proceeds to run and jump around the house in delight, while the pop