A short while ago (at the time of writing), Cracked.com published a video asking guys who make sexist comments on their videos towards the female comedians there to stop. Just stop it. It was partially presented tongue-in-cheek, and they made sure to present the actual comments as bluntly and obviously offensive as they were, so the point got across.
Then a few weeks later, they released a parody video about Final Fantasy and the illicit recreational drug-like use of phoenix down for resurrection. It was funny, but it also included all the Cracked columnists in FF costume, including Katie Willert. With a bare midriff. Stretching her arms backwards at one point.
Obviously the comments included a few along the lines of "Katie, you can't tell us not to make sexist comments, then dress like that and do those things." Actually, yes she can dress like that and act that way without being said to invite sexist comments. That's victim-blaming, the old (and wrong) "but she was obviously asking for it" argument. It doesn't work in real life, and it's not working online. So Katie Willert can continue dressing up as a Final Fantasy game character, or in any other costume she wants, and that is not "asking for it", no matter what you think "it" is. That is the real point of the first video. Nobody is asking for it.
Mokalus of Borg
PS - For some reason this is especially prevalent online.
PPS - Because people are awful, when you get right down to it.