She's no moon

1. femme fatale;

2. hot girl who you don't want to get involved with, who you know is trouble, but whose presence is so strong you can't avoid being drawn into;

3. as in Episode IV of the Star Wars saga, when the Millenium Falcon is approaching what is left of Alderaan, Han Solo points out to a "moon", in which Ben Kenobi replies "That's no moon". They are then caught in the tractor beam of the Death Star, realizing their initial curiosity had led them into serious danger.

Guy 1: - "You know Vera? She's hot but she's trouble."
Guy 2: - "Yeah, man. She's no moon."

Another guy: - "Watch out for her, dude. She's no moon."