On stage, watch a feisty Katy Perry SHOOT DOWN a fan’s ex-boyfriend

OK – so we always suspected that Katy Perry wasn't the kinda gal that you mess not. 

But then, we love the Roar songstress for her ability to speak up and speak out. 

And it seems that Ms Perry isn't afraid to put her critics firmly in their place either – especially when they're questioning her singing ability.

At a concert in Melbourne, staged as part of her massive, on-going Prismatic World Tour, Katy asked a fan in the audience for her phone so she could take a selfie.

Upon inspecting the device, however, the singer realised that the woman was in the middle of a WhatsApp conversation – and that the guy at the other end of the messages had stated Ms Perry "couldn't sing live at all".

Responding, the 30-year-old megastar takes a selfie, which she duly sends to her detractor along with the scathing line: "You thought I would never see this chat. You dickless monkey. You have no balls, pussy. C***."

Ouch.

Katy is also horrified to hear subsequently that the man is actually an EX boyfriend of the concert-goer.

"What are you doing?" she asks. "Do NOT text your ex."

It seems that the incident took place late last year – but has only came to light over the last few days when the lady to whom the phone belongs shared the interaction online.