"Hammerhead" is the second single from Australian rock musician James Reyne’s debut self-titled solo studio album, released in 1987.The track featured uncredited backing vocals by Olivia Newton-John. Reyne reflected on the song saying: ""Hammerhead" was not necessarily about me, but let's say I thought I knew what I was talking about. I wrote it with Simon Hussey; the music Simon and I wrote together and I wrote the lyrics. From memory it seemed to come quite easily. I shouldn't make too much about the fact that it's about drugs. It can be taken many ways. It was an exercise in trying to write a song about that subject but to also make it that it could be about a relationship. It's a song about a relationship. And whether that relationship is with a substance or a person, it's an obsessive