As Seen on Cinemax After Dark...
From an interview with Alexandra Robbins, author of Pledged: The Secret Life of Sororities:
[The sorority] had a tradition called boob ranking where pledges had just a limited amount of time to strip off their shirt and bras to examine each other topless so that by the time the clock was up, they were basically lined up in order of chest size in order of [sic] the sisters to inspect. Some sororities hold what they call "naked parties," during which after a few drinks sisters and pledges strip off their clothes and basically run around the house naked, some of them hooking up with each other before they let the boys in.