fangirl

A type of human female who obsesses over something, usually a book/book series, TV show, celebrity, or anime; this behavior is called fangirling, hence the name; you will find them staying up till early in the morning reading fanfiction as well as using words such as OTP and ship

Regular person #1: That's a fangirl over there.
Regular person #2: How can you tell?

Regular person #1: You mean besides the fact that she's squealing about her OTP to her fellow fangirls?