While I personally find O'Conners activism to often miss the point entirely and pass up meaningful action for symbolic outrage, she absolutely nails things in this open letter to Miley Cyrus.
http://www.theguardian.com/music/2013/oct/03/sinead-o-connor-open-letter-miley-cyrus
http://www.theguardian.com/music/2013/oct/03/sinead-o-connor-open-letter-miley-cyrus