A bored Helen started the mischief making by deciding to mess with everyone's clothing, before a pair of disgusting *s** t stained crusty knickers" got her attention.
Ash suggest: "Put them on Mark's pillow as he'll react the best."
And he wasn't wrong as a raging Mark complained: "Who the bloody hell did that? Absolutely disgraceful. I'm absolutely raging."
He warned the housemates as Helen and Ash giggled on: "I'm going to go f**king nuts again. Some dirty f**ker has put them on my bed."
Mark later told Christopher who was advising him to relax: "It's not funny. My head is really done in. I am f**king fuming."
He went on: "I f**king hate liars, I've asked everyone in this house and somebody's lied to my f**king face.
"I don't know who would find that f**king comical. Whoever things that's funny needs to go to a f**king doctor."
At this point, Ash piped up: "I thought it was funny."
Mark hit back: "I think you need to go and f**king sort your head out cause it's sick. I think you did it."
"I think you're overeating," Ash replied.
"I think I'm not overreacting , I think it's massively f**king disrespectful."
Watch the prank, dirty knickers and all, below