I think everyone knows that songs can be moving, happy making, dance inducing, and, well, annoying. My siblings and I discovered that "The Song That Never Ends" hit a particular nerve with our mother and might have spent a month or so singing it a lot. (Sorry, Mom. I still like singing it though.) I have been known to offer up the advice to folks with songs stuck in their heads that I could sing a different annoying earworm of a song. (In addition to "The Song That Never Ends", there is "It's a Small World" and a teen in youth group taught me "I Know a Song (That Gets on Everybody's Nerves".) I'm helpful like that.
And certainly the use of song in protest (by which I mean more official protest, rather than parental or sibling protest) is well known. But I'm heart-warmed by folks in Norway who have gathered to sing a song outside a courthouse. There is a man on trial for bombing a building and then going on a shooting spree. He has stated that his killings justified because his victims were being too left-wing and allowing Norway to taken over. In his comments, he mentioned the song "Children of the Rainbow" as the kind of silly multiculturalism he is against. (It's possible he used stronger wording.)
So, folks have gathered across Norway to sing the song. They gathered outside the courthouse in the rain to sing while his trial continued, to make the point that he does not represent the vision of Norway they wish to see.