Mainly girls, that are so jealous, they are almost psychotic. These girls are jealous of a boyfriend or a friend you have a 'thing' with, they will stalk this boy and make fun of you through wall posts on his facebook. Also, they arn't very pretty. Basically, they should get a life.
That girl is sucha jealous pyscho, she just made fun of me on my guy friends wall on facebook, and she wont leave him alone.