Speaking to The Daily Telegraph, she revealed that two contestants slept together in the villa's main bedroom where everyone sleeps.
"They high-five each other after and do a big thumbs-up. Everybody knows when it is going to happen. It hasn't happened every night, though."
She continued: "By the way, they wouldn't mind me saying that, they are pretty open about it all."
Recently, eliminated contestant Kim Hartnett also revealed that the show's X-rated moments don't make it to our TV screens.
She said contestants were "100 percent' having sex inside the house."
She told news.com.au, "It’s pretty obvious for the audience to know which ones are doing it."
While she abstained from getting intimate with Josh in their bed, Kim revealed there was one unnamed couple who were very vocal about their sexual exploits.
"I think the first night they did it they full-on had an audience, everyone was sitting up and watching them," Kim told the publication.
"Then it just got to the point where you were used to it. It was kind of like a bedtime lullaby, if they didn’t do it you’d be like, ‘what’s going on?’"