Watch: Former All Black Ma'a Nonu is brutally shut down by referee Wayne Barnes

Ex-All Black Ma'a Nonu now plays for Toulon. Photo / Getty Images

When former All Black Ma'a Nonu suggested referee Wayne Barnes show a yellow card in Toulon's clash against Scarlets on Sunday morning (NZ time), he was swiftly put in his place.

Nonu's Toulon side were awarded a penalty in their 30-27 loss, and when Nonu suggested more should have come from it, Barnes set him straight.

"Let's make it really clear: you come and ask for a yellow card, you get one. Understand?"

Football has long seen players mimic going to their card book when referees award fouls.

And speaking to the Daily Telegraph, fellow referee Nigel Owens admitted it was an unwanted trend that was now starting to creep into rugby.

"This is something we certainly don't want to see in the game," the 2015 Rugby World Cup final referee said.

"It's something we as a group of referees have discussed and agreed to stamp out.

Referee Nigel Owens wants to stop players from calling for cards during rugby matches. Photo / Brett Phibbs.

"We'll all have our certain ways of dealing with whether you penalise the guy who asks for the yellow card, where you call him over speak to him like Wayne [Barnes] did very well, and give him that warning, or do you give that yellow card and reverse the penalty decision?

"Every referee will deal with it in the way he feels appropriate."