“We were there on the floor when these dramas would emerge about slut-bashing,” Armstrong told me. “We saw working class girls walk out of their dorms to visit boys, and the privileged girls would say, ‘why are you wearing that?’"

As Armstrong and Hamilton write in a new study published in Social Psychology Quarterly, economic inequality drove many of the differences in the ways the women talked about appropriate sexual behavior.

All but five or six of the women practiced “slut-shaming,” or denigrating the other women for their loose sexual mores. But they conflated their accusations of “sluttiness” with other, unrelated personality traits, like meanness or unattractiveness. It seems there was no better way to smear a dorm-mate than to suggest she was sexually impure.

“If you want to make a young woman feel bad, pulling out the term ‘slut’ is a sure fire way to do it,” Armstrong said. “It’s ‘she isn’t one of us, we don't like her and she's different.’”

Because most of the slut-shaming occurred in private, women were both targets and producers of it, and it was rare for the term “slut” to stick to any one woman. Instead, the other women were simply foils for each others’ supposed sexual virtue. One woman described her best friend like so:

“She just keeps going over there because she wants his attention because she likes him. That’s disgusting. That to me, if you want to talk about slutty, that to me is whoring yourself out.”

For her analysis, Armstrong divided the cohort in two, with wealthier women in one group and the working-class ones in the other. Each group tended to band together, with the poorer half feeling excluded from Greek life and other high-status social activities. Several of the low-income students, for example, balked at the cost of the $50 "rush" t-shirt, Armstrong said.

The rich women tended to view casual sex as problematic only when it was done outside of steady relationships, and even then, only when it included vaginal intercourse. Meanwhile, frequent “hooking up,” which to them included kissing and oral sex, did not a slut make. “I think when people have sex with a lot of guys that aren’t their boyfriends, that’s really a slut,” as one put it.

The poorer women, by contrast, were unaware that “hooking up,” in the parlance of the rich women, excluded vaginal intercourse. They also tended to think all sex and hook-ups should occur primarily within a relationship.

The two classes of women also defined “sluttiness” differently, but neither definition had much to do with sexual behavior. The rich ones saw it as “trashiness,” or anything that implied an inability to dress and behave like an upper-middle-class person.

One woman, for example, “noted that it was acceptable for women to ‘have a short skirt on’ if ‘they’re being cool’ but ‘if they’re dancing really gross with a short skirt on, then like, oh slut.’”