A state when a girl has a strong partially unhealthy, attraction to a boy she like and thinks about him constantly. The symptoms often include, Long hours creeping photos on face book, becoming excellently nervous around said boy, forgetting her name when introducing her self, and vomiting.
Can also appear in gay boys who don't know how to date.
Girl: look there is the boy I like, I'm going to go over and talk to him.
Girl's friend: I don't know, you seem to have a severe case of Teen Girl Syndrome, is that wise?
Girl: No, I'll be fine, really.
Girl walks over to boy
Girl Hi, I'm... *Vomits on boys shoes*
Girl returns to her friend in shame
Girl's friend: You threw up on his shoes again didn't you?
Girl: I think he likes me.
Girl's friend: I'm sure.