The singing along being optional part is a bit surprising for us here, since here and in the surrounding countries, it's all about the public singing, without necessarily having any artist perform - see link for an example (though you're missing out on the usual camera floating past every player's face to let the TV viewers check if he's singing along...). But then, we have national anthems which were written as such and intended to be sung along to - the Star Spangled Banner is a bit different as a song.