Johnson, known in Britain and beyond for his often outlandish persona and dishevelled mop of platinum hair, said his country would not turn its back on the world after Brexit and cast the United Kingdom as a cosmopolitan consumer of imports.
"We are gluttons in this country for imports. We buy huge quantities of stuff, particularly of course from our friends in the European Union, as of course we shall continue to do so when we do that great free trade deal," he told ambassadors.
Johnson quipped that Britain had even managed to export Brexit campaigner Nigel Farage, who enjoys a friendship with President-elect Donald Trump, to the United States.
"We managed to export Nigel Farage to America," he said, before joking about May's decision to be photographed wearing fashionable full-length leather trousers that British media said had cost £995 ($1,260).
[caption id="attachment_39957" align="aligncenter" width="800"]
Britain's Prime Minister Theresa May, 3rd from left, and left to right, David Davies Secretary of State for Exiting the European Union, Foreign Secretary Boris Johnson, May, Chancellor of the Exchequer Philip Hammond and Home Secretary Amber Rudd sit opposite a Polish delegation during an intergovernmental consultation meeting in the Cabinet Room in 10 Downing Street in central London, Britain November 28, 2016 Reuters
"We are so cosmopolitan that we drink more champagne, more prosecco, buy more German cars than anyone else and our wonderful prime minister actually wears lederhosen," he said, using the German word for traditional Alpine leather shorts.
Johnson denied a media report that he had privately told some EU ambassadors that he supported freedom of movement, one of the EU's fundamental citizenship rights that was established by the 1992 Treaty of Maastricht.
Britain wants to control immigration from EU countries as part of Brexit, though EU leaders say Britain cannot have full access to EU markets if it does.
"The last time I spoke to so many ambassadors, I'm afraid a rather curious account of what had I said emerged ... perhaps the media misunderstood something," Johnson told ambassadors at a reception in London late on Tuesday.
"I am in favour of the free press, I am in favour of freedom of speech, I am in favour of free universal suffrage, I am in favour of free drinks which you are all having tonight but I am not necessarily in favour of freedom of movement," he said.
It was not the first time that Johnson and May seemed to be on different wavelengths. Last week, May slapped him down after video emerged showing him saying Saudi Arabia was stoking proxy wars across the Middle East.