The Brussels boss reduced French prime minister Edouard Philippe to fits of laugher as he made the grim and downbeat analogy about his upcoming meeting with the UK premier.
It was a humorous reference to excruciating details of the pair’s last supposedly private dinner, held at Downing Street, which were leaked to a German newspaper by Mr Juncker’s chief of staff.
On that occasion, back in May, the British side reacted with open fury to the embarrassing leak forcing the chief eurocrat to apologise and admit it had been a misjudgement.
But Mr Juncker could not resist opening old wounds this afternoon when asked by reporters what he expected from tonight’s dinner, which will also be attended by David Davis and Michel Barnier.
He initially stonewalled, responding: “I have never understood why journalists, even the most eminent journalists, ask for the outcome of a meeting before the meeting takes place.”
But then, as Mr Philippe turned away and giggled, he added: “Yes, I’m going to see Mrs May tonight and you’re going to have the report of it. It will be the post-mortem report.”
It is not the first time Mr Juncker has used the phrase in a humorous way to discuss policies. However, his remarks came at a sensitive time and just minutes after the EU Commission insisted the dinner is not even technically about Brexit, dashing British hopes it could herald a major breakthrough.
And one EU official said that “nothing has changed” since the two sides met last week for the latest round of negotiations, meaning any new developments on the divorce proceedings front are unlikely.
Asked about the dinner, EU Commission chief spokesman Margaritis Schinas said: “This is an informal dinner where the prime minister and president will discuss broader issues of European and geo-political common interest.
“One shouldn’t forget that the EU Council is held at 28 but also at the long-term G7 and G20 agenda where the UK is an important partner. Both leaders asked their chief negotiators to be there but the policy menu is broader than that.
“The Commission has been given a unanimous mandate of 27 of our member states to negotiate Article 50 and this is a process which is ongoing and is not strictly related to the dinner. The dinner has a broader agenda.”
Asked why the dinner was only announced so late in the day – it was not included in the EU Commission’s calendar published on Friday – he said it had been “on the agenda for a long time” but the pair had only recently agreed a date.
British officials said the EU and UK teams are expected to discuss Brexit – something which would go outside the bloc’s formal negotiating framework – as well as counter-terrorism and the situation in Iraq.
A spokesman for Mrs May said she was hoping for a “constructive” meeting with Mr Juncker, but confirmed she would not use the dinner to make Brussels a new offer on the financial settlement.
He added that the get together was “part of the process of achieving a smooth Brexit” and that she would also hold talks with French president Emmanuel Macron and Irish Taioseach Leo Varadkar today.
The meeting comes after the Brexit talks hit “deadlock” last week, with Britain and the EU still in disagreement over the thorny issue of a Brexit bill. Both Mr Davis and Boris Johnson publicly – and Mr Barnier privately – have urged EU leaders to loosen their negotiating strategy to kickstart progress.