The incident came moments after Marnie and Saira had a row, when the ‘Loose Women’ star became upset at some of her housemates branding her patronising.
Former ‘TOWIE’ star Lewis then dared Marnie to go over to Saira - who was having a separate conversation with Christopher Biggins, James Whale and Grant Bovey - and issue a prank apology for their argument by saying she felt it happened “because I have better tits than you.”
She preceded to do so, but took the dare one step further by pulling down her top and shoving her breasts in Saira’s face.
Many viewers deemed Marnie’s actions to be akin to sexual harassment, calling for her to be ejected, with others pointing out that Aaron Frew was removed from last year’s civilian series of ‘Big Brother’ over a similar incident.
James Whale was also disgusted by the incident, and told Marnie her behaviour was “completely unnecessary”.
“She does not deserve that- stop it,” he said.
Turning to Saira, he added: “That could make me really angry but I won’t let it. However I will tell you Saira, you won’t have to deal with that again I can assure you.”
A ‘Celebrity Big Brother’ spokesperson declined to comment when contacted by HuffPost UK.
‘Celebrity Big Brother’ continues tonight at 9pm on Channel 5.
Take a look at more ‘CBB’ controversies in the gallery below...