The NYT reports that nude parties are popular at Yale and Brown. One commentator suggests:
“The dynamic is completely different from a clothed party. People are so conscious of how they’re coming across that conversations end up being more sophisticated. You can’t talk about how hot that chick was the other night.”
One senior remarked that the skinny people look ugly. A graduate "describe[d] the parties as an overload of the “liberal college environment where everyone’s talking about unfair conventions, post-structuralism, ‘boxes.’ I don’t know.”
I would expect the parties to be more socially egalitarian, given that clothing cannot be used for social signalling, or for that matter for social concealing. I would expect less flirting, less drinking, less aggressive behavior, less lying, and more social seriousness. These effects should also wear off over time, as people get used to nudity and develop other means of signalling and concealing. Presumably there is informal data on such questions from nudist societies, although such groups may have greater selection biases than nude parties in the Ivy League.