A lone figure takes to the stage, a giant maple leaf flag rippling on a screen behind him as he gingerly approaches the microphone.

“I’m not a lumberjack, or a fur trader,” he tells the crowd. “I have a prime minister, not a president. I speak English and French, not American. And I pronounce it ‘about’ – not ‘a boot’.”

The crowd, indifferent at first, grows increasingly enthusiastic as the man works his way through a catalogue of Canadian stereotypes, passing from diffidence to defiance before the climactic cry: “Canada is the second largest landmass! The first nation of hockey! And the best part of North America! My name is Joe! And I am Canadian!”

The ad, for Molson Canadian beer, was immensely popular when it aired in 2000. And now, with Canada’s identity and sovereignty under threat, it has roared back into the public consciousness.

In recent weeks, Canadian patriotism has surged in response to Donald Trump’s suggestion that the US could annex its northern neighbour. His threats have prompted an outpouring of disbelief and defiance, but – in a very Canadian way – they has also revived questions over the complexities of national identity.

Trump began his campaign of diplomatic trolling before he had even assumed office, questioning Canada’s viability as a nation, suggesting that it could become the 51st American state, and deriding the prime minister, Justin Trudeau, as a “governor”

In response, Canadians have taken to acts of patriotism, small and large: one pilot flew his small plane in the shape of a maple leaf; sports fans have booed US teams; hats insisting “Canada is not for sale” have gone viral; consumers have pledged to buy only Canadian-made products – a pledge skewered in a viral sketch in which one shopper berates another for buying American ketchup.

Related: Canada’s Liberal party was left for dead, but Trump might have just given it a second chance

“What the hell are you doing?” he asked “We’re in a trade war, you traitor!”

“It’s been absolutely crazy and overwhelming,” said Dylan Lobo, who runs MadeInCa, a website that catalogues products made in-country. “We’re struggling to keep up with all the listings. People are really frustrated and they want to find a way to support Canadian and buy Canadian.”

Politicians, aware of a looming election, have wrapped themselves in the flag. And in a show of bipartisan unity, five former prime ministers have called for Canadian unity.