Off Topic - Geek Cred

Editor's Note: Most of the entries here deal with the LGBT community and the issues that affect us as a group.  However, from time to time Adam and I will want to share things from our personal lives. 

There are a lot of communities in which people seem to need to possess a certain amount of cred to be considered a real _______.  There are street gangs, there is sports fandom, and more and more, we're seeing that it is present in certain circles of nerdiness, particularly when a female wanders into the fold.  Nerds hate the "fake" nerd girl.  Why?