"Knock, Knock" "Who's There?"
"Donald Trump" "Donald Trump Who?"
It is an old joke but still raises a smile.
The real question though is; Now he's gone, will he be forgotten?
There is a growing school of thought, widely shared on the rolling news shows that dominate political discourse here in the US, that something called Trumpism exists. Whether he attracted 75million, 70million or 65million votes - who knows! - a sizeable wedge of the US electorate voted to give President Donald Trump a second term. Based on this, the steel-haired presenters and their wonk-ish TV guests argue that despite the shortcomings of Trump himself, the ideas and values he stood for can be codified and survive beyond the single term he served.
I'm not so sure.
First, I'm not really a fan of 'isms'. The ones which do survive and rumble on through history - Fascism, Communism, Socialism, Capitalism, Nationalism - tend to be rooted in an idea rather than any one personality and it is adherence to these beliefs which lasts and endures.
Those 'isms' which are derived from a personality tend to fair far worse, even when the person they are associated with was seemingly successful at whatever they did. In the UK, the political ideologies of the two most successful post-war PM's -Thatcherism and Blairism - failed to really endure beyond the protagonist. Often, the next-in-line inherited an inferior cast, a weaker script and couldn't deliver the lines with such aplomb. Like Hollywood sequels, they quickly became a pale imitation of the original and at the next big box office moment - lead to the end of the franchise.
In the US, where politics has always been pretty homogenous, favouring slight adjustments to the tiller of USS America rather than dramatic changes of course - 'isms' are generally disliked. They smack of ideological extremism - McCarthyism for example.
So, not wanting to be remembered as fringe or intolerant, those who do want to leave a lasting impression look for alternative definitions to hang their hats on. Reaganomics, a term whimsically coined by radio broadcaster Paul Harvey, makes the The Gipper's legacy sound much more thoughtful and academic than any strident and astringent 'ism'.
So, for me, if not the Fox News pundits, it is difficult to imagine how an unsuccessful personality like Donald Trump could spawn a trademarked 'ism' of his own with any type of shelf life.
If Trump is to leave any kind of 'ism' legacy, it is probably as an example of Populism - the belief that he represented the concerns and interests of those who considered themselves disregarded by the established elite.
Populism is a well worn path for the Right in politics. The Left has largely failed to harness it's undoubted power, opting for revolution instead. Even in seemingly tolerant Europe we see a number of administrations who have harnessed angry disillusion with the status quo, and successfully wrapped themselves in a flag of populist mantra to disguise their and their supporters' raw anti-immigrant, racial or religious bigotry.
Don't get me wrong, I would never say most Trump voters are racist or bigots - I know some and I like them - but I would hazard that most racists and bigots voted for Trump.
Trump was a populist of sorts. Through relentless social media shouting he was hugely successful at building a political constituency of pissed off baby-boomers, veterans, small government libertarians and traumatised suburbanites. They were reinforced by an army of ALL CAPS religious zealots, survivalists, bigots, racists, white supremacists and whack-job conspiracy theorists and, as with any success in US politics, remarkably well-funded by the big banks and hedge funds, offshore corporations, fossil fuel and extractive businesses through "low regulation, low tax" PACs and arms-length campaign finance loopholes.
But power and money for their own sake were Trump's real motivations. He wasn't driven by any wider concerns. He liked the trappings of absolute power. He saw himself alongside the Putin's, Kim's and legions of military clad dictators. He liked the parades, the flags, the fly-bys and the uniforms. But he mostly liked money. His hotels charged for his security detail to stay there while he played golf. Trump raised an eyewatering $300million in a week after the election to ostensibly pay for the legal challenge to the result, though closer inspection revealed the money was spent to settle his outstanding debts and unpaid bills from the election.
That he appealed to and was considered credible by a collection of typically financially insecure, non-college educated, rural and socially conservative voters, is even more remarkable when you recall he was a draft-dodging, silver-spoon, metropolitan-elite philanderer - everything they profess to hate!
But such remarkable circumstances will shape his legacy - it will be one of manipulation and irregularity not a lasting political doctrine.
So as President Trump walked up the steps of Air Force One for the final time, I'm convinced this is the last we will see of him as a political force majeure.
I think his personal focus will be on the impending legal and financial challenges he faces, wriggling clear of as much accountability as he can rather than worrying about a political ideological legacy.
But a dynasty? - wait, that is something which would appeal to the 45th President.
Donald Trump Jr? Ivanka?
Martin Liptrot is a long-time US resident with a British passport. He writes, broadcasts and consults on politics, corporate responsibility and public affairs from his home on Florida's Emerald Coast.