Can Theresa May resist temptation to mock Boris?
Theresa May is going to have to start taking Boris Johnson seriously if she wants the world to do likewise.
Last night I sat on the same table as the foreign secretary at the Spectator Parliamentarian of the Year Awards. He was given a gong for "comeback of the year" after his failed leadership bid propelled him into King Charles Street.
Mr Johnson gave a typically self-deprecatory speech, saying he hoped he would last longer than Lord Heseltine's mother's dog, Kim, which survived partial strangulation by the Tory peer only later to be put down.
He spoke about the need to press on with Brexit, which he described as taking "the machete of freedom to the brambles of EU legislation".
He told a funny story about how he had recently caused confusion at a dinner with EU colleagues in Bratislava: he said Brexit Britain would support the EU from the outside, like a flying buttress; the interpreters translated this as a "flying bucket".
And of course, there was the inevitable verbal slip when he promised that Brexit would be a "titantic success", a classicist's reference to the mythological giants rather than the ill-fated ship.
Then the prime minister got to her feet. I shall pass over her venomous assault on Sir Craig Oliver, David Cameron's former communications chief, except to note that several senior Tories were stunned by her lack of grace.
One - almost speechless - said it was the most unprimeministerial thing they had ever heard.
But it was what Mrs May said about Boris Johnson that struck me most. Picking up on his reference to Lady Heseltine's aggressive Alsatian, the prime minister looked directly at her foreign secretary - I was directly in the eye line - and said: "Boris, the dog was put down... (pause)... when its master decided it wasn't needed any more."
It was a funny line. And we laughed. But it also struck me what a barbed line it was too. It was a warning as much as a joke, a threat of political euthanasia for a colleague if he stepped out of line.
I also noted that this was, yet another, occasion when the prime minister had chosen to mock her foreign secretary in public. At the start of her conference speech last month, before the serried ranks of Tory faithful, Mrs May said there were many questions hanging in the air, including: "Can Boris Johnson stay on message for a full four days?... (pause)... just about."
Now every government has a court jester and Boris Johnson will never be able to escape that title. But his role in this government is crucial. He is there to convince the international community that Britain is not turning its back on the world post Brexit, that Britain has a positive role to play in global affairs.
And to do that he needs to be taken seriously. Many foreign politicians and diplomats that I speak to tell me they are pleasantly surprised when they meet the foreign secretary for the first time.
They talk of the man behind the caricature - the cultured, over-educated intellectual who often speaks a bit of their language and who can be thoughtful when he is not gripped by banter.
The problem is that many others - who have not met the foreign secretary in person - often still see him as a kind of upmarket Nigel Farage, a Eurosceptic clown with clout.
So to do his job, Britain's diplomat-in-chief needs of every bit of credibility he can lay his hands on. He is already the butt of many jokes. The last thing he needs is his prime minister adding to the mirth.