Amid the welcome confusion of cups and cakes a certain physical decency established itself.
Overwhelming events can cause a mental freeze in the participants. The mind races to absorb the inflow of sights, sounds and emotions, but the cascade of signals piles up into a mass of unintelligible phenomena, the mind freezes and loses fine-grained control of the body. In this situation, the most important thing to do is: anything. Take any action to break the freeze, preferably one that is productive to the moment or at least not wholly inappropriate.
Gatsby, Nick and Daisy are locked in an excruciatingly awkward social moment, but all it takes is some cups and cakes to break the freeze.