Former TOWIE star Lauren starred in last summer's series of CBB and was quick to give her opinion on the new housemates while watching at home.
However, it seems she's not too keen on acid-tongued Katie. In fact, Lauren even claimed to not know who she is!
The Essex reality star tweeted: "Who is this big nose ugly witch..Look at it, loves the attention..What a horrible weirdo! Worst clothes I've seen! If I was in the house with her..."
Lauren then posted an angry emoticon face alongside her message.
Many fans were quick to respond to Lauren and she later retweeted her rep, who had commented: "Can't begin to imagine how you would've coped with #CBBKatie."
Lauren then added: "Not going 2 lie, she will make brilliant TV but what an absolute loon! She literally hates everyone. Feel sorry for her housemates."
Katie was the first of this year's celebrities to enter the CBB house last night and straight away she was given a secret task by Big Brother.
After arriving in the compound, Katie was challenged to become an Enchanted Mirror for the evening, hiding behind a two-sided mirror to observe the other stars arriving and give her honest opinion on them.
She then had to tell BB who she thought were the "dullest" housemates - and she picked Chloe Goodman and Alexander O'Neal. The pair were then told by BB that they face eviction, however Katie was not revealed as the mastermind behind the decision.
Celebrity Big Brother 2015: The official lineup
Copyright: Channel 5