S&M means not sex & (whatever)!!!!
Listen to the song: "The sticks and the stones will break my bone, but chains and whips excite me!"
It means BDSM - Bondage - Domination - Sadism - Masochism
It is a Sex-game with pain.
S&M stands for sadism & Masochism, sadism means that you get pleasure from inflicting pain or by humiliating someone and Masochism means you get pleasure from receiving pain or by being humiliated, so sadists and masochists are basicaly meant for each other and that relationship is the foundation of bondadge, whiping for pleasure and the dominatrix