Survivor NZ contestant Adam O'Brien got a huge dose of Botox injected into his forehead before he left for Thailand.

Before he boarded the plane for Thailand to compete on Survivor NZ, Adam O'Brien went to a Botox clinic.

He pointed to his forehead and told the technician, "Just make sure this doesn't move, eh?" She injected 36 units of Botox. A typical forehead treatment is about 14.

If O'Brien makes it Survivor's final three, he'll have spent at most 40 days living in the Thai jungle. It'll be about three months before he can move eyebrows again.

His goal was to enable him to conceal his emotions when he's on the show. To make him hard to read.

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"In terms of reading people's energy and stuff, a lot of it comes from the expression on your face, and I raise my eyebrows and squint at people and stuff," he says.

O'Brien plans to keep his Botox treatment a secret until the end of the show. "I really want to play the relaxed character," he says.

O'Brien, 29, lives in West Auckland and is self-employed doing construction administration. He grew up in Te Awamutu, Waikato, but "hated" the rural life. "Definitely not me. Not my kind of people or scene," he says.

Survivor isn't O'Brien's first brush with reality TV - he made it to bootcamp on X Factor Australia in 2013.

His interest in Survivor comes from an interest in human behaviour. He says he's always wanted to be part of a social experiment.

"I love sassy people, I love angry people, I love Debbie Downers, all of it is interesting to me. If everyone was nice it would all be the same," he says.

On Survivor, he'll be in a prime position to watch the drama unfold. But will he be able to turn it to his advantage? Perhaps it depends on whether his opponents can read his poker face.