'Nearly fainted': Matty Johns 'rattled' by son's brutal prank

Matty Johns is no stranger to playing pranks on people, but the rugby league funny man has been given a taste of his own medicine.

The best part: it was his own son Cooper that stitched up the league legend in one of the simultaneously cruel yet hilarious ways possible.

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The young Storm star decided to go along with a gag from Sydney radio duo Kyle Sandilands and Jackie O that centred around a joke about Cooper's "real father".

Melbourne's 21-year-old playmaker asked his father on-air about a rumour he said was bugging him about Newcastle Knights legend Kurt Gidley being his actual father.

Cooper said speculation from online trolls had gotten to him and asked his father to set the record straight, prompting Matty to brush it off as nonsense.

“Oh mate, please, people say to me all the time how much we look alike,” Matty said.

“My first instinct is to laugh but at the moment I can’t really work out how serious you are. One-to-10, how serious are you now?”

Matty then did the maths in his head - albeit inaccurately - and insisted that the 38-year-old Gidley was far too young to be the 21-year-old's father.

“Well there you go mate, so obviously he fathered you when he was 14. Come on, it’s a gee-up," Matty said.

“Any concerns you might have, they’re unfounded … you’ve got more chance of winning Lotto three nights in a row.

“But mate, if you’re really, really concerned about this, then you’re probably better off having the discussion with your mother (Trish).

“Seriously, there is absolutely no chance.

Matty ‘nearly fainted’ over final suggestion

Keen to string his dad on a little longer, Cooper then asked if Matty would go on his own show on Fox Sports to confirm that he was indeed the biological father.

Matty explained that doing do so would only perpetuate the rumour and told Cooper to ignore the trolls.

However, it was the next part of the prank that really got to Matty when his son then asked if they could get a paternity test done.

“F*** mate, now you’re rattling me,” Matty said after a period of stunned silence.

Sensing the joke had gone on long enough, Kyle and Jackie O then jumped in to put Matty out of his misery by revealing that they'd put Cooper up to the brutal joke.

“I tell you what, you’re lucky you jumped in. I was about to tell him his real dad is (Channel 9 presenter) Richard Wilkins,” Matty joked.

“Honestly, I nearly fainted.

“That silence you heard, it was me concerned. Not about the DNA test — I hate needles.

“I’m still rattled.

“I’m going to have a beer.”