(I apologize in advance for the sheer number of links in this post. All are valuable resources, including definitions and papers.)
I am a a cisgender, pansexual, white, middle class female. I am able to pass in society without having to deal with my existence being questioned. My gender is apparent to most people, I do not have to deal with race if I choose not to, and I can enjoy privileges based on my ascribed status. I am fat, though I have seen how I am treated change with how my body changes.
I read a blog post by Katie at kataphatic.wordpress.com that discussed Linda Bacon’s paper based on her keynote speech to NAAFA (National Association to Advance Fat Acceptance). In the post, Katie quotes Linda Bacon: “The cultural perception of fat bodies as “wrong” hurts those of us in the “right” bodies too. … Inequity hurts the oppressor as well as the victim.”
This is exactly the reason why I discuss privilege, even while not in a minority groups. Even if my gender is not immediately questioned based on my appearance, it is a simplistic cultural artifact that needs to be questioned. And, it needs to be questioned by those that appear and/or are cisgender, and not just those that live publicly and appearance wise as genderqueer. Those that are living in white bodies should be questioning why those in non white bodies do not share the same privileges and access to resources as we do. Those of us in male bodies should be questioning why they have advantages that are not afforded to those in female bodies. Those of us in thin bodies should question why we have such an obsession with thinness and weight, and how it is to the detriment of all people (especially women) in society.
Because oppression hurts all of us. Rigid roles based on ascribed status and appearance limit everyone. This is not meant to minimize the daily struggles that one goes through as a person who has an appearance that is not the “average” or expected, but as a reminder that the struggle is not limited to those who outwardly express it. We must all question the status quo, even if we firmly fit within it.
(How does this relate to sex? The more comfortable one is with their body and identity, the better their sex lives 
And, the ability to play with these concepts within sex and a sexual/romantic relationship can be a safer space to learn more about them.)