A Gender Bender is a person that does not conform to expected gender roles and behaviours that are established by society.
They “bend” between the genders.
They may wear clothes that are normally worn by the opposite sex, or they may be participating in activities that are mainly associated with the other gender.
“Gender Benders” are often assumed to be trans, queer or somewhere on the LGBTQ scale, but some do it in the name of social activism and to destroy irrational gender roles and expectations.
A “Gender Bender” who is originally male may dress like a woman, or a biological woman may dress like a man.
Or, they will dress completely androgynous so that other people may have difficulty figuring out if they are looking at a woman or a man.
“Gender Bending” could stem from the 60’s and 70’s identity politics activism, it’s objective being that personal identity is political.
The term started showing up in written documents as part of the LGBT linguistics in 1970, but has been part of the gay vernacular for a long time before.
In the magazine called Gay Sunshine, writer and known “gender bender” Christopher Lonc published an article with his motivations for being a “gender-fuck” (another word for “gender bender”) in 1974.
His motivation was to ridicule and destroy restrictive sex roles.
Drag shows are a big part of the “gender bender” culture, in which men dress up as fabulous, sassy women and perform extravagant and vulgar entertainment shows.
In pop culture, a significant fraction of the biggest rock and alternative music bands between the 70’s and 00’s turned to “gender bending” and cross dressing, both as activism and to create their own identities outside the societal borders.