Genderfuck is a form of gender expression that seeks to subvert the traditional gender binary or gender roles by mixing traditionally masculine (such as a beard) and traditionally feminine (such as a dress) components. It literally means to "fuck with" or mess with traditional notions of gender expression or gender roles. For some it is their gender identity, for others it is a label for a certain events clothing or outfit.  This may also extend to the belief that the social construct of gender does not exist.
Genderfuck as a form of identity
Some people may feel like genderfuck is the best descriptor for their identity, as they in general feel it applies to them not only in expression but also in their personal feeling of gender. People who identify as Genderfuck may often use parody and/or exaggeration to show how intensely it has broken traditional gender roles. They may want to expose them as fake, artificial or absurd by using ones own expression to create an image that fits in neither traditional box and thus may spark discussion or disagreement.
Genderfuck people may share many things with genderqueer, but they are separate identities.
Genderfuck as a form of expression
Some binary identifying trans people or nonbinary people may choose to intentionally dress up in a genderfuck outfit for an event or photoshoot. This usually consists of using secondary sexual characteristics of different sexes such as a beard and breasts, or another expression of traditionally male and female identifiers together. This may be to intentionally confuse the audience and to set traditional gender roles and expression into question, leading to discussion under the umbrella of "what is masculine/feminine?" or similar discourse.
Genderfuck also seeks to break down the rigid binary space and create a new fluid space where people can express and qualities they want of themselves without being ridiculed for "not fitting in your box." More open room to express oneself however you find comfortable. This is also often used by Drag Queens and Drag Kings when performing as they do not use just feminine or masculine qualities in their outfits and intentionally dress up in a way that cannot be limited to feminine or masculine qualities.
Although this is often associated with queer identities, you do not have to be queer to want to or to participate in genderfucking.
Genderfuck as a term has been used since the 1960s 1950s. It stems from a political movement which states "the idea that the personal is political."
A very detailed article can be found here.
Lonc wrote: "I want to criticize and poke fun at the roles of women and of men too. I want to try and show how not-normal I can be. I want to ridicule and destroy the whole cosmology of restrictive sex roles and sexual identification."
- Dictionary definition of what Genderfuck means: https://www.dictionary.com/e/gender-sexuality/genderfuck/
- LGBTIA+ Wiki about Genderfuck: https://lgbt.wikia.org/wiki/Genderfuck
- Wikitionary about Genderfuck: https://en.wiktionary.org/wiki/genderfuck
- Wiki page on Genderbender / gender bending: https://en.wikipedia.org/wiki/Gender_bender
- Urban Dictionary on Genderfuck: https://www.urbandictionary.com/define.php?term=genderfuck
- Wiki on Genderbender Drag section: https://en.wikipedia.org/wiki/Gender_bender#Drag
- This is from a book which you can find links to here: https://lgbt.wikia.org/wiki/Special:BookSources/0870238787