PARIS: No, they’re the Puffs, the most influential sorority at Chilton.
RORY: Chilton has sororities?
PARIS: Only ten worth mentioning, and the Puffs, they have been number one for at least the last fifty years.
A sorority is a women’s social organisation at a college or university, the female equivalent of a fraternity. They were once common in US high schools as well, but these days many schools ban them. However, they are still in existence, and some schools are willing to turn a blind eye to them while not recognising them officially.
We learn here that Chilton is the sort of school which tolerates this practice, and that it has at least ten major sororities! The Puffs have been the most powerful and exclusive of them since at least 1951.
The current Puffs seem to consist of Francine “Francie” Jarvis (President), Ivy, Dijur, Lily, Celine, Lana, Asia, Anna, and Lemon. The name Puffs could have been chosen in-universe because of powder puffs, suggesting a fashionable femininity, or even that they are delicious little morsels, as puffs are such a favourite food in Gilmore Girls. However, it suggests being filled with their own importance (“puffed up”, “puff piece”) and full of hot air.
There’s something insubstantial about the Puffs, as if a puff of wind could blow them away – remember that Rory even pretended a draft of air is what drove her to their table, taking her on a trip to another world just as weird and bizarre as Oz.