1. Definition and Core Concepts Sissification (often shortened to “sissy”) is a niche but prevalent BDSM and fetish practice in which a person assigned male at birth adopts exaggerated feminine characteristics, behaviors, and roles, typically within a submissive or humiliating context. Unlike simple cross-dressing or transgender identity, sissification is explicitly eroticized and often tied to power dynamics, emasculation, and psychological transformation.