The Great Gatsby takes place in the 1920's. During the 1920's the law of prohibition had been passed. Many people rebelled from it and would not obey this law. People sold alcohol illegally and would pass it around at big parties."
Jay Gatsby was a big part of this problem. He was a bootlegger. Through this illegal operation, Gatsby was able to make a lot of money and become a part of the "new money." He was a smuggler and a consumer of alcohol in the 1920's.
Flappers were the women's style of the 1920's. These fashions contained bobbed hair, thin, knee length dresses, pearls, etc.) Women like Daisy, Jordan, Myrtle, and most of the women in this book followed this fashion because they were a part of the people that were rebelling against the laws that they believed were unjust.