Mr Sutcliffe's pledge follows a ministerial spat over medals
Minister Gerry Sutcliffe has bet his shirt on one of the fiercest rivalries in world sport: Britain v Australia.
The sports minister promised to wear the Old Enemy's green and gold if Team GB is beaten in the Beijing Olympic medals table.
Meanwhile, his Australian counterpart is offering to don red, white and blue if Britain does better.
In 2004 Australia won 49 medals and GB 30. A government spokesman said: "Green is not really Gerry's colour."
The Olympic rivalry was stoked when Culture Secretary Andy Burnham predicted Great Britain could overtake Australia in Beijing.
Australian sports minister Kate Ellis retorted by saying British athletes might "choke" under the pressure of competing at the highest level
She followed up the claim with a sartorial wager.
Mr Sutcliffe told the BBC: "Kate Ellis has challenged me that, if Australia win more medals, then I would have to wear their shirt at a UK event, and if we won more medals she would do similar in Australia."
A Department for Culture, Media and Sports spokesman said: "There has been a great sporting rivalry with Australia and that will continue in Beijing.
"It's good to see that Kate Ellis is showing the courage of her convictions by having a bet with Gerry.
"We hope that it is her donning a British top in Australia after the games rather than vice versa."
Australia and Britain have a sporting rivalry going back further than the modern Olympic Games - founded in 1896 - themselves.
Most famously, cricket's Ashes have been competed over since 1882, with England - including Wales's Simon Jones - winning in 2005.
The trophy was snatched back with a series whitewash in 2006/07.
In rugby union, England have knocked Australia out of the last two world cups.
However, in rugby league, of which Mr Sutcliffe is a devoted fan, Australia currently reign supreme - having beaten Great Britain in the last Ashes series.
In the 2004 Olympics in Athens, Australia's 49 medals, including 17 golds, put it fourth on the overall table. Great Britain's 30 medals, including nine golds, put it 10th.
Bookmaker William Hill has Australia at 1/2 to maintain superiority in Beijing, with Team GB on 13/8. Punters can get 14/1 for a tie.
William Hill's media relations director, Graham Sharpe, said: "Australia are expected to struggle to keep up their medals tally. Britain's most optimistic outcome is about 41 medals.
"If the Aussies are not quite up to their best they might be overtaken. They have had wonderful times, but I suspect we are on the up and they are about to decline gracefully.
"Mr Sutcliffe is still an outside bet not to lose his shirt, though. I don't suppose anyone will mind seeing a politician with egg on his face if that happens."
More than 200 countries are taking part in the Beijing games.