Prohibition: Women like this would come together because they were against alcohol and drinking. They would make up mottos like "Lips that touch liquor shall not touch ours", stating that they will have no interest in anybody who drinks.
The Charleston dance became extremely popular in the especially with Flappers. The flappers had a beautiful style that was easier portrayed in posters, as their long dresses created movement to represent the Charleston.
The Bob was the most popular hairstyle of the time. Headbands were also used as accessories in women's hair. Some women did not want to fully commit to having short hair, however, so they would have a fake bob and curl up their hair and pin it.
Dress like a Flapper. Then throw a nifty Gangster Party, and use these Gangster Props. They are printed on a clear sheet of plastic material. You would cut the Gangster Props out and place them on your wall with double sided tape or thumbtacks.