Couple things..
First off, canadian's flag plenty. I have a canadian flag on my skis, there are countless flags flying throughout my town and i know several people sporting 'Canada Kicks Ass' t-shirts. There's nothing wrong with being proud of being from a certain country. It's when you brag about it and seem to constantly push your patriotism on other people. I live in a very tourist oriented town, and work at a resort in the winter, american's are ALWAYS more then happy to tell you they're from the states and many like to compare canada to the USA often pointing out what's wrong with canada (everything but the beautiful and pristine wilderness). Not all american's do this, but a surprising amount do.
As for Canadian's fighting in afghanistan with the american's, i believe an american fighter pilot who was a little trigger happy disobeyed a direct order and killed 4 of our men. Fuck, i don't even want to think about what americans would do if a canadian fighter accidently bombed several american soldiers. We'd be hated.
Since people are already talking about their 'victories' at war, do any american's know about the time canadian kicked their asses with half the men (was in half, or were the odds even worse then that?) and a quater the budget when american's tried to invade canada a couple hundred years ago? After winning, we proceeded to burn down part of the white house. That story seems to come up a lot less...i guess it's been forgot south of the border.
Speaking of forgotten, on 9/11 canadians took in hundreds if not THOUSANDS of americans whos planes were grounded in canada. Many canadians took the stranded tourists into their homes and fed them. Gymnasiums were set up as temporary shelters, i went to give blood that night to do my part, and the line up was out the door and down the street. Of course, Bush accidently forgot to thank us in his speach, though he didn't write it himself and it was mearly an oversight.
Also, somebody mentioned americans doing more for other countries then any other country. Well, that's because you have friggen 280 million people paying taxes. Canada and other countries have a decent amount of money going out to other countries aswell (at 30million, canada can't exactly put up as much), but again, american's feel the need to brag, even though the tax dollars are the result of a dense (crowded in my opinion, unless you live in kansas) population that's riddled with crime. Oh and can you say 'free health care for all'? Nope, but you can sure say '300 billion dollar millitary budget'. I suppose i can't complain there, i get free health care, and canada gets protection because of american forces. I can deal with that one just fine, though it would be nice if they didn't use that power as a barganing tool with the UN who is supposed to represent peace. I believe they USA is the only member country who's soldiers CANNOT be held accountable for their actions in a millitary court. If the UN even tried to, the US would quit the UN, thus screwing them over. And that's why the pilot who bombed the canadians, and the guy who decided that bombing a wedding was a great idea won't be explaining their actions in a UN court.
The problem doesn't lie in american's being patriotic, it's the fact that they get so patriotic, it often comes across as though they think they are somehow better then everyone else. I don't mean to trash the USA in this, even though i sorta did, Americans just need to be aware that they're not so great...it's a great country, but not worth bragging about.
Hell..maybe i'm completly wrong on this, it could be that everyone else just feels inferior to the might US of A, but then again, maybe not.