It stands for Sadomasochism. Sadism is pleasure in the infliction of pain or humiliation upon another person, while masochism is pleasure in receiving the pain. These practices are often related and are collectively known as sadomasochism as well as S&M or S/M. These terms may be used clinically, in psychotherapy, to describe mental illnesses, psychopathology or counterproductive coping mechanisms. Additionally, these terms may describe consensual practices—often sexual, but not necessarily so—within the BDSM community.
Almost positive it means secs and money. :\ I don't know why song writers have to use that kind of junk in songs; there are plenty of other things to write about other than junk like that.