The term refers to popular and well-liked figures, who are found to have done something questionable in their past that damages their reputation.
Macquarie Dictionary has chosen its Word of the Year for 2017, encapsulating a year defined by a seemingly endless stream of revelations about well-known figures, and stars falling into disrepute.
Inspired by a meme by Australian cartoonist Ben Ward in 2016, a "milkshake duck" refers to someone seemingly above reproach – but who is revealed to have a dark secret that colours how the public feels about them.
Macquarie Dictionary editor Susan Butler said there have been many instances of milkshake ducks.
"The milkshake duck is presented as this cute duck that loves drinking milkshakes, and everyone falls in love with it, and two seconds later it's revealed as being racist, so suddenly everyone has to turn around and hate it."
She cites Don Burke as the most prominent Australian example, although Burke denies the allegations made against him.
"Everyone's favourite gardener is suddenly the person that everyone draws back from in disgust," Ms Butler said.
"I think we're now always nervously expecting the next milkshake duck to happen.
"We're just waiting for someone to milkshake duck."
Panellist Dr Karl Kruszelnicki agreed 2017 provided numerous milkshake ducks.
"There was a lot of 'this person gets elevated, and then falls down again'," he said.
Its creator appeared to acknowledged the irony of his own social media fame in a later tweet which said: "It is terrifying that I created a meme that will destroy me when I inevitably do a problematic tweet. Milkshake Duck is my sword of Damocles."
Runners-up include "plandid", which refers to a supposedly candid snapshot that has actually been set-up, while people who unquestioningly follow trends are called "sheeple".
Ms Butler says politics has also had a big impact, introducing words such as including "ghost tax" for taxes on people who buy investment properties that are left unoccupied, and "wage theft" for when employees do not receive the pay or benefits they are entitled to.
According to Dr Karl, generational influences were also prominent, leading to "smashed avocado generation" for the generation reaching maturity from 2010 (and who, according to reports, spend all their money on avocados).
"What that implies is that 'oh they're too busy spending their money on frippery, to put down a deposit [on a house]', but the point is – they're not going to be able to find half a million dollars as a deposit," he said.
"I didn't vote for that one, I thought it was too mean."