Horst Seehofer had looked set up to run up an enormous tab at the famed P1 nightclub when he offered everyone on his Facebook page a free drink if they showed up - and several thousand said they would be there.
But luckily for Seehofer's Christian Social Union's budget, most of them stood him up, leaving him with around 500 people – including more than 100 journalists.
They were treated to the sight of conservative Bavarian politicians off duty and keen to make friends with the Facebook generation.
General Secretary Alexander Dobrindt, 41, arrived in skinny jeans and a natty scarf, while Seehofer, 62, himself wore his top button undone, the Süddeutsche Zeitung reported.
The CSU chairman delivered an off-the-cuff press conference, in which he covered topics as diverse as his children's "pre-lash" habits and his own Facebook postings, according to Der Spiegel magazine.
"I get the ideas when I'm the car," he told a throng of around 120 journalists, though he confessed that an internet-savvy assistant was charged with posting his musings.
Adding to the surreal atmosphere was the presence of figures from the Pirate Party. The party's Bavaria chairman, Christian Körner, presented Seehofer with a membership card, while another Pirate representative accosted Bavarian state Interior Minister Joachim Herrmann, asking him to rethink his stance on the legalisation of cannabis.
Despite the disappointing attendance, CSU figures judged the event a success. Seehofer has swelled the ranks of his Facebook fans from 2,000 to 10,000, taking him comfortably ahead of his presumed rival in next year's state elections, the SPD's Christian Ude.
The Bavarian premier told the Süddeutsche Zeitung newspaper he was already planning another party, which would go ahead "regardless of how tonight goes."
That is likely to the nightclub's owners, who imposed a novel interpretation of the ‘free drinks' policy – apparently revellers who ordered a mixed-drink with their Seehofer token were told their refreshment of choice was in fact two drinks, and as such would set them back €9, Der Spiegel said.