A cache-sexe is an item, often a small garment, that covers its user's genitals. The most common style, seen in Western G-strings and Japanese Fundoshis, has a triangle of material (cloth, beaded strings, etc.) attached at the corners to straps or strings around the waist and between the legs, that fasten the triangle over the genitals.

Cache-sexes have various social intentions, including the wearer's practice of sincere or enforced modesty, legal and/or customary restrictions within the context of intentional eroticism, and adding fetishistic or playfully teasing aspects to intentional eroticism. In Western cultures, for example, G-strings appear as swimming attire; for many erotic dancing venues, as the final state of undress, set as the polite and/or legal limit; or as a garment whose removal is one of many steps of a striptease, each existing to provide an increment in the viewer's sexual arousal.

Cache-sexe is a loanword from French.

Cache-sexe is also an alternate term for modesty plate, sometimes caping, a small triangular or heart-shaped jewelry worn to hide the genitals, typically made of silver, gold, or brass.