Sam Wilson shared his life with a man he detested for two days in an effort to win the £10,000 prize in a reality TV show.
And despite being stalked, ridiculed and threatened he still managed to get the last laugh.
Sam, 24, of Gloucester Road, Brighton, scooped £10,000 after convincing his family and friends his house guest from hell, Simon, was his best friend.
Every step of the hoax was filmed as part of a new television programme called My New Best Friend, which saw Sam become the star of his own Big Brother.
Sam was looking for a job on the internet in February when he stumbled across an advert offering £10,000 for anyone who could keep a secret. London production company Tiger Aspect invited him in for an interview.
He was told a man he had never met would come into his life during a specified period and he would have to pass the man off as his friend.
Sam's flat was rigged up with dozens of hidden cameras and he was later fitted with a hidden microphone.
Simon, played by an actor, appeared when Sam was having breakfast with a friend at Kensingtons Caf in Brighton on a Saturday in March.
That night, Sam hosted a party and Simon plastered dozens of Polaroids of him on to the walls, to convince his friends he was a stalker. He aggressively defended Sam against any criticism. His act was so convincing, one of Sam's friends hid the knives in the kitchen.
Sam said: "I told my friends I was okay with it but in reality I was finding it very difficult. They thought I had taken this guy, who clearly had issues, under my wing."
On the second day he accompanied Sam to meet his mother for lunch. She does not like the music scene so Simon spent the whole time convincing her the two were about to set up a band. Simon showed her the Polaroids and told her Sam was at risk from a stalker. The game came to an end after lunch when Simon made his exit.
Sam's performance secured him the show's jackpot. His friends were given £250 for being unwitting participants.
He said: "I have no regrets because I'm £10,000 richer and my friends thought the whole thing was a laugh. Even my mum saw the funny side."
The episode will be broadcast on Friday September 5 on Channel 4.
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