In front of 30,000 screaming Australian fans on Monday night, British pop star Harry Styles raised a sweaty sneaker full of water to his lips and drank.

“This is one of the most disgusting traditions I’ve ever heard of,” he told the Perth stadium, grimacing before downing the drink to deafening chants of ‘shoey, shoey, shoey’.

Post-swallow, Styles told the raucous crowd he felt “like a different person”.

“I feel ashamed of myself,” he said, shaking his head. “I’ll be discussing this with my therapist at length. At length!”

Styles is just the latest international star to be subjected to the questionable Australian trend that is the shoey: drinking a beverage, usually alcoholic, from a shoe.

F1 driver Sir Lewis Hamilton, actor Sir Patrick Stewart and a slew of musicians – including rapper Post Malone, Machine Gun Kelly and country singer Kasey Musgraves – have partaken while visiting the country, usually at the insistence of Aussie supporters.

But the trend is divisive. Many Australians say it is tired, gross and “blokey”; an embarrassing thing for the country to be known for.

Others say it’s a harmless bit of fun rooted in Australian culture – which values self-deprecating humour and a sense of egalitarianism.

No-one is sure where the shoey originates from.

“Like any cultural tradition, a few people try and claim it,” Liz Giuffre – a communications lecturer at the University of Technology Sydney – told the BBC.

There are rumours soldiers did shoeys during the World Wars, as did Russian ballet stars long ago.

But the earliest shoey Dr Giuffre has found photo evidence of took place in 1951. American actress Tallulah Bankhead was captured sipping champagne from her heel during a press conference at the Ritz Hotel in London.

But what started as a show of “opulence” at some point evolved into something “silly” in Australia, Dr Giuffre says.

Mark Gwynn, who has been researching the word to add to the official Australian National Dictionary, says the shoey is a fairly recent phenomenon in Australia.

The first references he can find date back to 2010, when the shoey was associated with the Australian punk music scene, but was also a feature at parties and sporting matches. It’s typically done to mark a celebration.

“It’s a triumph over adversity thing… the whole idea that I’ve just done this really hard thing and I’m going to drink out of the shoe that got me there,” Dr Giuffre says.

But both researchers say the shoey – the word and the act – were undoubtedly popularised in 2016 by Australian F1 star Daniel Ricciardo. He made it his trademark race celebration and boosted its global exposure. It has only exploded in popularity since.

Australian golfer Hannah Green earlier this month celebrated with a shoey after winning her first tournament on home soil, and Nedd Brockman – who ran the width of Australia last year – finished his run with a sock-flavoured cocktail.