Blackfive commented at Serenity's blog on the hierarchy of countries that produce bar brawlers (which he posted on again today). His list follows my experience pretty well, with one addition that I'd like to make. The original list:
1. Don't fuck with the Aussies. They are number one. You might have to kill them to stop the fight.2. Don't fuck with South Africans. Not quite as rough and tough as the Aussies, but you think twice before fighting them.
3. Americans.
4. Brits.