(I wrote a version of this post last year and it prompted Bruno to coin the word "Pervocracy." So there's great sentimental value.)
In my sexual utopia, everyone is a man. Everyone is called "he," every boy has two fathers, every board has a chairman and fires are fought by firemen. Pilots are all men, presidents are all men, and kindergarten teachers are all men.
Of course, biologically, there are male men and female men, but frequently it isn't obvious and unless you're a doctor or very intimate it's insanely rude to ask about or comment upon it. It's private parts, dammit, and whether someone has a vagina or a penis is as inappropriate for public discourse as speculating how much pubic hair they have. (Obviously body shape and whatnot do give you some clue, but it's still not polite to comment. And moreover, it's not interesting; sure you can guess that a five-foot man with large breasts and wide hips is female, but that doesn't tell you anything important. It's like knowing his blood type; who really cares?)
And there are men who like to wear makeup and long hair and skirts, and men who'd rather have a buzz cut and cargos (and some sexy bastards with a buzz cut and a skirt), but it doesn't correlate with maleness or femaleness, it's just a personal choice. As are personalities and family and community roles. And when two men have sex or marry--well, every relationship is between two men so there's no real difference, is there?
(It'd be interesting to let this experiment run for a couple hundred years and see if female men behaved any differently from male men. My guess is probably a little bit, but nowhere near as extremely or consistently as in our current society.)
I guess the concept of a genderless society is hardly a new one, and all I'm adding is the idea of making everyone male. That's partly because English is already structured around male-default, and it avoids awkwardly artificial constructions like "hir", and partly because I think it's funny.
This is what the world would be like if I were King.