MKR star Manu Feildel went berserk when his 18-year-old son told him he had ruined his career with the South Sydney Rabbitohs by failing a drugs test.

Manu Feildel’s son Jonti played a cheeky prank on his father on Friday morning when he convinced the My Kitchen Rules star that he had failed a drugs test.

The 18-year-old, who has just signed with the South Sydney Rabbitohs’ junior division, told the 48-year-old celebrity chef he ruined his NRL career before it even started after a wild weekend of drug use.

But it was all a prank orchestrated by The Kyle and Jackie O Show because Jonti wanted to goad his dad.

Jonti told radio hosts Kyle Sandilands and Jackie “O” Henderson that he was nervous about calling his feisty French dad because “I have a feeling he’s going to explode.”

After some encouragement, he called the restaurateur who was staying at his hotel in New Zealand where he was filming.

“I messed it up, dad. Next week the bunnies will test us for drugs,’ Jonti begins.

Jonti (pictured), 18, who has just signed with the South Sydney Rabbitohs, told the 48-year-old celebrity chef he ruined his NRL career before it even started after a wild weekend of drug use

He continued: “I started smoking weed last weekend with my friends, so I’m not sure if it will be in my system or not.”

At this point, Feildel went ballistic as he berated his son: “Come on bro. light up. Nice. Shit Jonti. F**k, f**k, f**k, Jonti. light up. shit mate

“We talked about it. Mind your damn career, man. I don’t want to deceive you, Jonti. I really don’t want to blame you, but you know you have to grow up.’

But it was all a prank orchestrated by The Kyle and Jackie O Show because Jonti wanted to goad his dad. (Pictured: radio host Kyle Sandilands, left, and Jackie ‘O’ Henderson, right)

Feildel went on to say that he thought Jonti was already drinking too much and tried not to judge, “but now you smell goddamn Reefer.” What’s next? Nice.’

After more back-and-forth, Feildel finally calmed down and told Jonti that he understands what it’s like to make mistakes as an 18-year-old.

But when Jonti asked his father to pee in the cup for him so he could pass the upcoming drugs test, Feildel insisted his son take responsibility for his actions, even if it meant losing his place in the team.

Jonti told radio hosts Kyle Sandilands and Jackie ‘O’ Henderson he was nervous about calling his feisty French dad because “I have a feeling he’s going to explode”.

“It ends up being a damn slap in the face. A damn good lesson for the future,’ he said.

At this point Sandilands and Henderson interrupted each other to reveal that it was all a lie and that Jonti was not on drugs.

Feildel sounded relieved when he replied: “You bunch of idiots. Oh dear God. I was about to cry.’

Feildel “exploded” when Jonti told him he had “screwed it up”, but admitted he was “about to cry” when Kyle and Jackie O interrupted him to reveal it was all a joke