A gonk is a very stupid, ditsy girl that may or may not be a huge slut as well.
1. A sorority girl that wears her North Face jacket, Ugg boots, and leggings.
2. A girl that has absolutely no hobbies/past times besides going to the bars and getting drunk with her "besties."
3. Can even be used in referring to a "hipster" girl who thinks that she is cooler than everyone else, but in all reality she is still a naive girl that drinks PBR, uses a mac, and thinks she's a good photographer.
"Look at that group of gonks, all wearing their uggs."
"I went to the bars last night and all I saw were gonks."