If youre doing it in front of people who fought or benefit of those who died for your country to exist, I believe so. Im for being patriotic, because I think you should have some pride in whatever country you decide to call home (as well as take responsibility for its faults and not whitewash it, because every country has something bad about it), but other then that, id say it shouldnt be as big of a deal. as long as you actually get the words right its fine, because some (like the USA's) you have to be able to hit certain points vocally that can be challenging if youre not a professional.
... unless youre this woman
<youtube=Zw7CdgJdkv0>
She not only pissed on two countries national anthems (Fairly sure she said the USA's wrong and you dont break in the middle of yours to shout "let me hear you"), but also on the great sport of hockey itself! You madam should never be allowed to sing an anthem again, because Im fairly certain this isnt the first time you fucked up. hell, even the players are laughing at your terribleness.
EDIT:
Fatboy_41 said:
Zhukov said:
I dunno what you're on about... THIS is our Anthem...
-vid snip-
<spoiler=hunh, i could ahve swore it was always this><youtube=McsWKczU6wc>
Im only joking of course