Someone asked for a primer on Judith Butler's work and ideas, so here is a brief blurb. Judith Butler is an American academic who is most famous for advancing a postmodernism theory of feminism. The basic premise of postmodernism is there is no such thing as objective reality. Instead, the only thing that exists is 'discourse' or 'texts' - we humans socially construct our reality. What we think of as 'reality' is actually the dominant 'text', which has been put in place by those who are most powerful. For example, the idea of germs (as opposed to magic, or evil spirits) making you sick doesn't reflect reality as it actually is (because there is no reality). Rather, we think that germs exist only because that dominant discourse has won the day. These power structures are not neutral - they are also deeply oppressive. When one person declares reality to be a certain way they get to control what reality is.
Some areas of the discourse are involved in a constant power struggle, and one of these areas is sex and gender. The standard feminist view is that men made up the concept of gender in order to oppress women - women were put in the lower sex caste, with men being on top. And so the way to fix this is to get rid of gendered assumptions and say that men and women are equal, right? No, says Judy. When feminists campaign on behalf of women they are being just as oppressive as the men. The problem is that they assume there is such a thing called 'woman' which actually exists. This is erroneous. There is no such thing as 'women'. Women have been made up by oppressors, and so feminists are just copying their oppressive ways by campaigning on behalf of this thing which doesn't exist. By advocating for women, feminists actually create and make real the very category of 'woman' itself. That is bad because it makes feminists themselves oppressors, but it is also bad because it is exclusionary. To define something is by definition exclusionary - things are automatically put outside the 'woman' box. Like men. And black women (apparently. I find this point pretty racist. I don't think black women ever considered themselves to be outside the woman category.)
So how do we stop this horrible exclusion? We must accept that 'woman' as a concept doesn't really exist. Anyone can be a woman. Woman can mean anything. Once we accept that then the rigid categories break down.Judith Butler imagines a feminist movement that is reduced to 'playfully' deconstructing and riffing on what it means to be a woman.
Butler is also famous for her idea of 'gender performativity' which is actually rather trite. Butler thinks that gender isn't a real thing but is something we construct on a daily basis because we perform it. When I put on lipstick I am performing and strengthening the concept of 'woman'. So gender is something we make real by 'doing'. It is a social construction. Now, sadly, we can never get rid of gender completely. But what we can do is 'subvert' it or 'queer' it - basically taking the piss. So gender is 'subverted' whenever a man wears lipstick, for example. Or whenever a woman shaves her head. We can't get rid of gender completely but we can blur the boundaries between masculine and feminine and 'play' with it. And because gender is something entirely constructed, that we constantly make and re-make, this means that men can literally become women (because women literally create themselves as women everyday). There is nothing more to being a woman than performing the woman role.
If you want to read her directly, she's best known for her book "gender trouble'. But I warn you her writing style is really awful and designed to make you feel stupid. I must also warn you that because she just isn't clear about her ideas, and because she constantly contradicts herself, there is a lot of debate about what Judy actually means.