As a culture, we've come a long way from the old Men Are From Mars, Women Are From Venus assumption that the binary genders are just too different to ever understand each other.
And yet even as our understanding of the gender spectrum grows and our vocabulary becomes more adept at communicating about these things, there is still a lot men and women don't know about each other. That's probably why #WhatMenDontKnowAboutWomen got so much traction on Twitter.