We're not Brazil, we're Northern Ireland sing fans of the Northern Ireland international football team. Their song is an expression of pride and identity, which raises an interesting question: who exactly are the Northern Irish and how is their identity reflected through sport?
In simple terms, the Northern Irish are people who live "here", in Northern Ireland, but our identity is often defined in narrow terms and sport provides an insight into how diverse the picture is.
When it comes to identity, I often paraphrase the Ulster poet John Hewitt, who laid out neatly the hierarchy of overlapping identities which he felt personally. He described himself as a Belfast man, from Ulster, who felt Irish and British, with those two identities being interchangeable.
He also felt European, and said anyone who demeaned any of those aspects demeaned him.
Today we could add further layers of complexity to this picture, as so many people have come to Northern Ireland from around the world to make this place their home. They add aspects of diverse cultures and backgrounds to what it means to be Northern Irish.
The experience of sports competitors and fans and their flexible attitudes can illuminate how we understand Northern Irishness. They also raise an ongoing challenge for sport's governing bodies to reflect Northern Ireland's existence by using symbols and emblems sensitively.
Sportspeople and fans have allegiance to towns, villages or parishes. Sometimes allegiance is determined by county, for instance in Gaelic games, or youth football, where county sides compete for the Milk Cup.
There are Irish provincial teams like Ulster Rugby. Then, a number of teams represent Northern Ireland at international level; the Irish FA's teams, and sports like netball and volleyball.
At the Commonwealth Games sportspeople who engage in sports organised on an all-Ireland basis such as boxing and athletics can represent Northern Ireland.
Northern Irish sportsmen and women compete for all-Ireland teams. Rugby, hockey and cricket are three examples where there have been efforts, with varying degrees of success, to use symbols associated with the island as a whole rather than its states, or to reflect both jurisdictions through emblems and anthems.
At the Olympics Team Ireland represents the Republic and Team GB the UK, strictly speaking, and use symbols and anthems reflecting the two states.
Many people from Northern Ireland support the Republic's football team, and the FAI's decision to choose Northern Irish players is an example of sports eligibility causing controversy.
Complicated layers of allegiance don't stop there. Rugby has the British and Irish Lions while Great Britain and Ireland compete in golf's Walker Cup.
At the Ryder Cup our wonderful golfers play for Europe. And, in cricket, although Ireland has its own one-day team, cricketers from these shores pursue test match ambitions for the England team, which selects players from across the UK and the Republic.
The fluidity of identity and allegiance is demonstrated at the current Rugby World Cup, where an Ulster player from New Zealand plays centre for Ireland.
Sport reflects accurately the many influences, cultures and identities which make Northern Ireland unique. We're privileged to be at once British and Irish, with no contradictions at all between those two identities.
Most importantly, we share a beautiful part of the world and we're all Ulstermen and Ulsterwomen: Northern Irish, with all the richness and complexity that that entails.