According to the Peg Songfacts, I'm Eighteen Songfacts, this was Alice Cooper's first hit. They had a very popular stage show, but their first two albums didn't sell well. If this didn't produce, they probably would have been dropped by their record label. It did reaching #21 in the US.
Lines form on my face and hands
Lines form from the ups and downs
I'm in the middle without any plans
I'm a boy and I'm a man