Can be in reference to a female who Steals your clothes, breaks into your house, sleeps in cars, badmouths you to everyone because she's the ugly unloved one and wishes she could be like you.
Tries to sleep with guys you know and is repeatedly rejected- though the one in the movie actually managed to sleep with the guy cause she dressed up like the prettier one.
Comes to your house out of the blue, begs to stay then goes through your black book trying to find a guy to talk to her.
The thing is no one seems to like her and youre warned by everyone you know to stay away or else or you may end up like the victim in the single white female movie.
sarah turned into a single white female when her friend got everything in life she didnt.