'Slag'n'Drag". "Geeks and Sluts". "CEOs and Corporate Hoes". Freshers' week has returned – and so have the misogyny-themed parties and club nights. Some events are depressingly institutional: Carnage UK – who flogged a Pimps and Hoes night in Cardiff last weekend – has been running sexist student events across the country since 2004, boasting endorsements from magazines such as Loaded, Nuts, and Zoo.

But other events have taken a worrying new twist. Everyday Sexism, a blog that collates thousands of stories about misogyny, reports a new sexist tactic: the slut-drop, where male students offer a lift to women stumbling home from a club – then leave them miles from where they asked to be dropped off. It doesn't sound dissimilar to kidnapping.

So: is behaviour getting worse on campus? How widespread is slut-dropping? "I've only heard one example of it," says Laura Bates, founder of Everyday Sexism. "I don't want to suggest it's a national trend. But it is just one example of what seems to be a disturbing wider phenomenon. On the one hand, women are being told that they've got to go to all these club nights dressed like a slapper or a slut. And on the other hand they've got these boys deriding them for that. It's a double bind."

Amy Masson, women's officer at Sheffield students' union, hasn't heard of slut-dropping, but has noticed that promoters are using ever more sexist language to sell their club nights to students. "Because the club trade is in decline, clubs are getting more aggressive with their marketing strategy and are using overtly objectifying images to try and fight for that smaller slice of a smaller pie," she says. "They are handing out flyers outside the student unions that promote sexual assault on nights out. The attitude of the promoters is that you will go on a night out, find intoxicated young women and have sex with them."

At Warwick university, women's officer Alys Cooke hasn't encountered slut-dropping either. But she can easily see it happening: it's some distance from the clubs to the campus, and students sometimes need lifts. She laments the ubiquity of sexist-themed student nights. "When people come up with fancy dress themes, there's a pressure to have at least one option so that the girls can get their clothes off." The internet has also helped to normalise misogynistic student behaviour, Masson says. Lads' sites such as Unilad and Toplad, which cater for undergraduates and that have emerged in the last three years, make it easier for men with sexist attitudes to establish a collective identity online. "This week I organised a protest against the Carnage theme," says Masson. "On the Facebook page for the event, somebody told me to 'get raped, you whore'. The internet gives people the opportunity to bounce off one another with these sexist ideas unchecked. If someone raises an objection, they're immediately told to get raped. It the ultimate anti-feminist breeding ground."

Lads' websites argue that their misogyny is meant in good humour. That's disingenuous, says NUS vice-president Toni Pearce. "The casual trivialisation of these despicable insults normalises dismissive attitudes towards women and perpetuates the idea that anyone who complains about sexual violence is humourless." Casual misogyny doesn't happen in a vacuum: according to an NUS survey, one in seven female students have been the victim of a serious physical or sexual assault.