Sexual practices that are seen to be politically provocative or subversive are usually relegated to the category of kink. But is this justified?
Take, for example, sexual inversion.
To hang upside-down is to assume an abnormal physiological posture. To engage in sex in this position makes a bold statement about the rejection of established normalcy. Ordinary behaviors are widely accepted by the mass of humanity, but these established norms are often flawed.
To invert your body is to put a thumb in the eye of crass assumptions. It puzzles an unenlightened viewer. It subverts cultural norms.
To question authority, one must often act in ways that are not currently comprehended. New ideas require fresh directions in thinking. Novel ways of proceeding. New ways to engage in sex. But the avant-garde is, unfortunately, taboo.
Strange Origins of Modern Kink 