According to a senior civil servant who I know, the gag is that the Government is “weak and stable”, a delicious twist on last year’s Conservative election slogan of “strong and stable”.
It’s a fair bet that if the joke has reached the ears of Theresa May, who is not noted for her lively sense of humour, she won’t have found it funny, even though it has raised wry smiles on the Tory benches.
The hubris of that woefully misguided decision to call an election, and the breathtaking ineptitude of the way Mrs May fought it, remain a ripe target for raspberry-blowing.
But then the Prime Minister might reflect that the joke isn’t quite as barbed as it first appears, for it acknowledges that she has proved to be a survivor and achieved a measure of stability in office that seemed unthinkable just a few months ago.
In the wake of the election, Mrs May’s days appeared numbered. The impression of a vulnerable leader not in control of her own destiny was only reinforced when her party conference speech was wrecked by a hacking cough and a prankster with a fake P45.
The loss of three Cabinet ministers, including her closest ally Damian Green, capped what must have been the worst year of her two decades as an MP, and yet the vultures within her own party that seemed to be circling have receded at least a little way.
Weak she certainly is, but stable for now, because there is currently no credible candidate to replace her and see off the threat of a resurgent Labour Party.
It can’t be a comfortable thought for Mrs May that her security in office depends on being the least worst option as Tory leader, but that is the reality and in the short term it probably protects her from a leadership challenge.
However fervently she must hope that 2018 is the year when events start to run in her favour, it is fraught with dangers to her political survival.
A Cabinet reshuffle aimed at freshening up her senior team to give the Government a new sense of purpose is a possibility, but risks causing ructions and deepening the bitter divisions over Brexit within the Tories.
The fragile deal with the Democratic Unionist Party to get Government business done could collapse at any time, particularly if the people of Northern Ireland believe that they are being sold out over the post-Brexit border.
And Brexit looms over everything. Last year ended well, with a breakthrough over the divorce bill with the EU, but the really difficult work in establishing trade arrangements still lies ahead.
Rebels within the Tory ranks have already flexed their muscles, and are unlikely to shy away from doing so again, once the Government belatedly outlines its vision for the deal Britain is aiming for.
Whether Mrs May can secure that deal is another matter entirely. Despite the fantasies of ardent Brexiteers who continue to insist that the EU will dance to whichever tune Britain plays, there is no guarantee of a successful outcome or avoiding an economic shock.
But if Mrs May and the Conservatives start the New Year with trepidation, the man who faces her across the despatch box has every reason to be rubbing his hands with anticipation of what 2018 might bring.
Jeremy Corbyn can look back on a 2017 that was, by any reckoning, a personal triumph and an excellent year for Labour.
Even the fact that the party fell a long way short of winning the election did not dim its new-found optimism and sense of purpose.
Mr Corbyn has achieved immense personal popularity, and motivated a legion of young people to get out and vote, simply by being frank and open about his beliefs, which came as a breath of fresh air to a large section of the electorate sick of political platitudes.
In addition to that, he is a leader riding a wave of good fortune. He looks and sounds confident, whereas the Prime Minister does not. The weakness of the Government, and its internal divisions, are gifts to Labour.
The party can sit and wait for the Conservatives to tear themselves apart over Europe, or deliver a Brexit deal that alienates voters – or threatens to leave them worse off – and then reap the electoral rewards.
Mr Corbyn has reportedly told aides that he expects to be Prime Minister this year. Nobody sensible would bet against that happening, given the unpredictable nature of the Brexit negotiations and the possible consequences for the Government.
Weak and stable it may be for the time being. But that stability could vanish in the twinkling of an eye, and 2018 produce political upheavals to make the year just past look uneventful by comparison.