Appropriateness and Moral Condemnation: Why Sex Matters but Shouldn't.

From Dictionary.com:

in·ap·pro·pri·ate [in-uh-proh-pree-it]
adjective
not appropriate; not proper or suitable: an inappropriate dress for the occasion.
Synonyms
improper, unsuitable, inapt, unfitting.

Here's the difference between a scantily-clad woman and a scantily-clad man. The man will read as humorous and good-natured, people will laugh. However, people will interpret the woman's lack of "proper" attire with sexual aggression. Why? Simply speaking, women is not seen as equally human, thus she is instead interpreted as a desirable object for men to twist, churn, and fuck. If she were seen as human, rather than as a sexualized object, others would acknowledge the plethora of interpretations behind her partial or full nudity beyond those that are strictly sexual in nature. 

Whenever someone expresses their opinion that a woman is dressed "inappropriately" due to too much of her body being exposed, they're outwardly suggesting that a woman's body is inherently inappropriate. Now, why would a woman's body be inappropriate? Society largely limits female bodies sole purpose to that of a sexual nature. Juxtapose contemporary western society's mutual demonization of sex and objectification of female bodies, and the final result is confusing and contradictory. The idea that the female body is provocative by nature implies that a male's exposure to too much of the female form will "provoke" him to act out in a sexual way. This manifestation of reductionist sexist assessment of the reasons for which women exist continually promotes the notion that a woman's body exists solely for the sexual satisfaction of heterosexual men.

Women do not exist for the sexual satisfaction of men. They simply exist, and in their existence, their body will serve a multitude of functions. It is not our responsibility, as women, to shroud our bodies from men. Just as it is a woman's responsibility to understand the appropriate time and place to view a man as a sexual entity, so too is it a man's responsibility to treat women with the same regard. 

I do not shout sexual suggestions at men jogging shirtless down the street. I do not stare at men's crotches when they choose to wear body-hugging pants. I do not ogle at muscle-tee wearing men in the hopes of getting a glimpse of naked torso. We understand such actions as unwanted and inappropriate. So, why do all too many men feel entitled to stare at a girl's ass when she bends down to adjust her boot strap, or catcall women on their way to work, or wink at a woman in a sports bra at the gym? If I know when it is appropriate to sexualize a man's body and when it is not, I expect the same consideration from men.

The normalization of sexism complicates one's ability to effectively respond to it in the heat of the moment. How do you demonstrate the injustice behind one's comments when institutionalized tolerance has been so deeply ingrained in their minds that the speaker is both the victim and perpetrator? Here are some statements you could say when you are presented with a situation in which someone is morally condemning a woman due to her outfit choice:

"Why are you sexualizing her body? You're making me uncomfortable."
"Do you understand how your comments promote rape culture? You are suggesting that it is a woman's responsibility to not be sexualized without her consent, rather than the responsibility of men to not sexualize women against their will. This mentality leads society to think women who dress a particular way are 'asking for it' and invalidates their experiences of sexual misconduct.
To school administrators/fellow students:
"Do you think it's appropriate to humiliate female students and make them ashamed of their bodies?"

Or, just straight up:
"Stop creeping on that woman. What's inappropriate about the flesh, bone, and muscle that together make up her legs?"

The most effective responses aim to educate, rather than perpetuate feelings of shame and humiliation, the individual/group of individuals who are making such comments about the implications of their words. Yes, there are men who are elitist assholes who act as if they are God's gift to women, but unless you have reason to believe otherwise, as the patriarchy encourages men to behave in such a light and not recognize the consequences of their behavior, you can often assume the ignorance of the perpetrators.