Until the air is alive with chatter and laughter, and casual innuendo and introductions forgotten on the spot, and enthusiastic meetings between women who never knew each other’s names.
In this passage, people — most notably the women — are in their own world, not interacting with each other and only caring about themselves, which Fitzgerald suggests is the default attitude to which people from the upper class resort around others of the same social standing. Also, the people are pretending to do the stuff that they believe high class people are supposed to do, as if there existed an unspoken set of rules which they must follow in order to seem like they belong in the aristocracy.
The young ladies at the party evoke an image of modern-day sorority girls, who are stereotyped as being obnoxiously loud and very exaggerated when interacting with one another.
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