I'm going to comic con in San Diego an I really wanna dress up but I don't know what to go as. Any suggestions?
You can wear a unique fancy dress such as the one featured at http://themixster.com/the-official-comic-con-cheat-sheet/. The dress has to be among the three categories which include casual fan, original character and otaku or cos-player outfits.
Usually people go to comic con because they actually have something to dress up as based on a show or music thing they like. Dress up as your fav anime charecter or webcomic charecter, or you can be a vocaloid charecter :D!