The Flower of Scotland, from Wikipedia:

Flower of Scotland (Scottish Gaelic: Flùr na h-Alba) is an unofficial national anthem of Scotland, a role for which it competes against the older Scotland the Brave. In common with England among the Home Nations, Scotland has no official national anthem. Flower of Scotland was written by Roy Williamson of the folk group The Corries and presented in 1967[1]. The song refers to the victory of the Scots, led by King Robert the Bruce over the King of England, Edward II, at the Battle of Bannockburn in 1314.

The song is a particular favourite of Scottish national rugby union team fans, who first adopted it for the Lions tour of South Africa in 1974. The last two lines of each verse are generally sung with particular ferocity, especially before games against England. Although not officially part of the anthem, after the line “and stood against him”, it is customary to chant “against who?” or “England!” after which follows the line “Proud Edward’s army” in the official part of the anthem. The Scottish Football Association adopted Flower of Scotland as its official pre-game anthem in 1997 although it was first used by them in 1993, following the Scottish Rugby Union’s example. Usually only the first and third verses are sung.

The introduction of Flower of Scotland was partly due to hostility amongst rugby and football fans toward the British national anthem God Save the Queen being used to represent Scotland, there being no other suitable anthem at the time. The song was popular amongst rugby supporters and was finally brought in as an unofficial anthem in response to God Save the Queen being continually drowned out by the ferocious booing and whistling of some of the Scotland supporters.

A public petition was presented to the Scottish Parliament in 2004 calling for another song to be selected instead.[2]

One snag with Flower of Scotland is that it is difficult to play on the bagpipes. The third last note is a flattened seventh, which is not considered to be part of the standard pipe scale. In order to hit the correct note, a ‘forked fingering’ must be used which less experienced players are unlikely to be familiar with. The tune was originally composed on the Northumbrian smallpipes, which play in F and have the benefit of keys on the chanter to achieve a greater range of notes.

And now a great example of some Scottish passion:

Makes me want to play rugby, or soccer, or just go to a pub and watch some! Speaking of which, February 14-15 of 2009 there’s gonna be a European rumble in the jungle! The 2009 USA Sevens Rugby Tournament is going to be held at Petco Park in San Diego. I’m going, who’s in?