Via Slashdot, apparently you are infringing copyright law and could be fined if you get caught singing "Happy Birthday to You" in public in Australia. The phrase has not only been trademarked, the 4-lines of lyrics has also been copyrighted by the Warner Chappell Music, and they won't expire until 2030. Aargh!! I've just realised that I have been stealing from the copyright holder every month when I sing this song to whoever had a birthday! My bad.