It's not often that I recommend a Reddit thread, but this one might be a real eye-opener for some guys out there. Reddit user aseriesofpipes asked, "Female Redditors, do you actually get creepy [private messages] when you self-identify as female? What's the 'worst' one you've gotten?" The answer to the first question is yes: When women 'out' themselves from internet anonymity, they often get harassed by creepy men. Let's restate: They are immediately harassed by men for the "crime" of identifying themselves as women.
And as to the second part of that question, look at some of these stories:
I posted a picture of me and my cat to [cute animal photo-sharing subreddit] /r/aww and someone sent me "I'm going to cut off your hair and choke you with it."
I got one PM that was just "CUNT CUNT CUNT CUNT CUNT CUNT CUNT" over and over. Not sure why but it made me laugh.
I mostly just get told to kill myself.
EDIT: I am, in fact, getting [private messages] telling me to kill myself just from this comment alone.
If you're a man and you spend time on the internet, I'd ask you to go take a look at the thread. Even if you consciously understand that women continually have to live through this kind of bullshit every day, it's a really visceral reminder that things are far from okay.