Russian comedians Vovan and Lexus released a recording of the phone call this week, where the fake Greta begs Canada to leave NATO, calls Donald Trump ‘a b******’ and requests a chance to meet South Park characters Terrance and Phillip – at which point the penny drops.
During the 10-minute call, a woman – playing the teenage climate activist – tells Mr Trudeau she is worried about a “growing international crisis and anticipation of the world war”.
“It already leads to disaster, it’s very scary," says fake Greta. Mr Trudeau replies: “Yes, indeed.”
The call took place days after the Iranian government shot down a Ukrainian passenger jet, killing 176 people on board, in January.
“You are adults but you act like children,” she says. “We can create a world where there is a place for everyone. For white and black. Christians and Muslims. Trump and Putin. For you and me. For Boris Johnson. For Corbyn. For Terrance and Phillip, who are also known in your country.”
“No, that is exactly, exactly, the right perspective,” Mr Trudeau responds, seeming to ignore the reference to two South Park characters.
He goes on to say that Greta’s visit to Montreal “helped define” the outcome of Canada’s election in terms of climate change.
But the prankster interrupts to say: “But leave Nato. Drop your weapons. Pick flowers. Smile at nature.”
A calm Mr Trudeau then replies: “I also dream of a world in which soldiers are not necessary, but we don’t live in that world yet, unfortunately. We need to push back on those that harm innocents.”
Fake Greta responds: “The main b****** is Trump because Mr Trump is doing everything to kill us." Mr Trudeau points out that he must work with “the world leaders that other people choose,” but added: “I can certainly understand that people can feel very, very strongly about him.”
The prankster also urged Mr Trudeau to take care of her friend Prince Harry when he moved to Canada.
The prime minister responded that Harry is “absolutely one of the good guys” and said he looked forward to spending time with him.
Mr Trudeau then says that Harry’s wife Meghan “has always been lovely when I've met her.”
Mr Trudeau finally realises he is being duped when fake Greta asks whether he can introduce her to Terrance and Phillip.
“I would be happy – I’ll ask my team to try and figure out how we can connect you,” he says. “Because I don’t have their direct coordinates with me now.”
“Wait, Terrance and Phillip, where they not in South Park?” he asks. “I don’t personally know them. I believe they are South Park parodies of Canadians,” he says, before politely thanking fake Greta and hanging up.
The Canadian PM’s office confirmed that the phone conversation had taken place back in January, adding it was “not the first prank call of a world leader,” and insisting that Mr Trudeau “determined the call was fake and promptly ended it.”