Perhaps you have heard of the phenomenon refered to as "mansplainin'"?
It occurs when a guy tells you something that you already know (and perhaps are even more well-versed in than he) in an extremely patronizing tone, as if to indicate: "Don't worry, sweetie. I'll clear up this complicated concept for you. Don't you worry your pretty lil' head about it."
Now, obviously patronizing explanations are something that pretty much every single human being in the world is guilty of every once in a while. Not all men mansplain, and lots of women are..umm...womansplainers? But mansplainin' is slightly different, because it is a specific type of explaining, and because it is a classic symptom of unexamined male privilege. This privilege enables a guy to feel like he is the authority on this particular topic (even when he's not), and to talk over you, patronize, silence you, and generally be convinced of his own superiority in all intellectual debates by virtue of his very existence.
One case, for your consideration: I am good friends with this one guy, in particular, who is generally awesome, but who is not particularly interested in gender studies. My volunteer work, which I have been doing for about a year and a half now, involves extensive work on the issue of activism and gender rights in Zimbabwe. Therefore, between myself and this male friend, I am the expert on this issue.
That did not prevent my male friend from telling me all about the situation in Zimbabwe, the political repression, and how President Mugabe is a bad dude (but first he had to be reminded of what Mugabe's name was). Over the course of like, 15 minutes. In a really slow voice.
This is the same male friend that once explained to me why shows like America's Next Top Model were bad for women's self-esteem. Thanks for the heads-up, bro. I totally didn't know that.
What about you? I'm sure you've had some annoying/funny/bizarre/perplexing experiences with mansplainin'! Tell me all about it.
To reiterate: not all men do this, and lots of women do this too. :)