Former Geordie Shore star Sophie popped up during this week's shopping task, which challenged the housemates to complete easy enough challenges without being distracted by the arrival of familiar faces.
Marnie's task was standing on a rotating piece of grass in the garden while remembering items that popped up at the windows of a fake house.
One item was Sophie!
After waving to Marnie and encouraging her to come over for a chat, Sophie left the house and told Marnie: "I'm so proud of you. I was on the phone to your mam today. Keep doing what you're doing, you're doing amazing and everyone is supporting you. Your mam, all the girls love you."
Sophie then turned to Marnie's boyfriend Lewis Bloor and said: "All she has done is smile, Lewis, she has… For everybody saying this is a showmance, can I tell you something? My cousin isn't a liar or an actress. This is real. Whatever is going on between them, please just let them be as they're having a good time. Don't get involved because she's happy and that's all that matters."
Watch Sophie's visit below!
Marnie and Lewis have been hit with showmance accusations because they both have the same agent, but their rep has denied they plotted their relationship and insisted they only met once in passing before entering the house.
It's certainly been a whirlwind romance for Geordie Shore's Marnie and ex-TOWIE castmember Lewis, as they exchanged 'I love yous' just 15 days into the show, and have already been talking about their future in the outside world.
Meanwhile, Sophie isn't the only familiar face to have entered the house this week. Bear was shocked by the arrival of ex-girlfriend Lillie Lexie Gregg, who confronted him about dumping her on TV and then hooking up with housemate Chloe Khan.
It all airs on CBB tonight at 9pm on Channel 5.
Fancy winning some GREAT prizes? Check out Reveal Competitions here!