how does myrtle behave as the party progresses?

As Myrtle drinks during the party she becomes more and more sexually promiscuous.

Myrtle begins to grow garrulous and harsh. Shortly after Tom gives her a puppy as a gift, Myrtle begins chanting Daisy's name to irritate Tom. Tom tells her that she has no right to say Daisy's name; she continues taunting him, and he responds by breaking Myrtle's nose.