Johnson discusses the relation between privilege and power. He says privilege is having something someone else is denied solely on the basis of race, gender, sexual orientation, etc. Privilege is not something that a certain group works hard for or deserves, it is a part of our culture's fear of difference and how we think we understand it by grouping and naming people. The big problem comes when groups of people use privilege to be superior to others. This brings in the +5 system, where people who are male, heterosexual, white, Christian and middleclass are most privileged (and therefore have the most power) and others fall below them based on how many factors they can match with these five things.
Power and privilege are inherited concepts. The privileged categories of people (white, male, heterosexual, etc) in our society have been in place for a very long time. Though changes have been made as to how these categories are viewed, the norm is that the +5 system exists and we want to be able to fit ourselves into the norm so that we can be recognized and considered "normal" in our society.
Using gender as a part of the + 5 system brings a lot of ambiguity to how being male is considered more powerful/ privileged than being female. Gender is something we alter in our daily lives to fit with certain situations or people. Because of this, there is a huge range of possibilities of what gender we are specifically acting in one particular, split-second moment of our day. So if all people "adjust" their gender constantly (though unconciously) through the day, the concrete "male/female" power hierarchy is limited by this ambiguity.