>>14246797Because if a male has sex with a female, she might be stuck with a difficult decision: kill the foetus or raise the child alone. Because of the strength difference, women may often feel compelled to accept male advances, especially in secluded contexts, out of fear of violence if they repel. Because of this, we traditionally let women have female-only secluded spaces (bathrooms, changing rooms etc.) so that they may do their private business without having to negotiate penises.
Wearing a skirt suggests you are pretending yo be a female, and intend to intrude into these spaces reserved for females, and disrupt their penis-free peace.