Cultures that endorse modesty and cultures that endorse hypersexualization are the *same* thing. Both define female sexuality by how it relates to the male gaze. In both cases the female body exists as an ornament either to be kept carefully hidden or put on display.
No means no, no matter what language it's in. I think the slut walk would be a great thing to participate in, because it generates publicity to make people aware of rape culture in our society, especially because of recent events in our history such as the Steubenville case. A girl was incapable of giving consent, that means no, but she was repeatedly raped anyways.