... and I use the term "peacocking" because a very popular style trend is based off of actual peacocks.
Photo Credits: Electric Laundry on Twitter @ElectricLaundr
The creative ceiling is boundless at raves you could see the cliche "sexy *insert a profession here* "
Like the lovely rave ladies you see below.
Photo Credits: http://www.vyneworld.com/
These costumes are classic and easy, but do not satisfy some ravers desire for individuality. So some go the extra step and make their own costumes, and they are interesting to say the least.
Photo Credits: http://imgarcade.com/
There are some things to keep in mind though when deciding what to wear to a rave, you don't want functionality to go completely out the window. You have to remember that you will be dancing and moving. So your clothing will need to be sturdy if you want to avoid any wardrobe malfunctions. Also you are going to want to use water proof make up. If not your sweat someone elses you brush up against could ruin your outfit.
For more information on rave fashion I recommend some, Google-Fu, individual study of the topic. Even if you are not that interested in the fashion portion of the culture the costumes are at least interesting to look at.