09/11/2009 at 09:00 AM EDT
In her new horror film Jennifer's Body
, Megan Fox
plays a possessed high schooler who eats any male classmate who gets in her way. In real life, the star says, she's not that
ferocious with her men – but they had better mind their manners.
"I don't like boys who are mean to their mommies," the star, 23, told PEOPLE at her film's premiere at the Toronto International Film Festival Thursday. "That's a real turn off for me. And I don't like boys who aren't chivalrous. To me, not being respectful is a big deal."
Despite her maneater reputation, Fox – whose relationship with former fiancé
Brian Austin Green can best be described as on again, off again
– says she looks for a companion who is "funny and has a good sense of humor" and likes a man who is tender. "I like someone who has a super gentle spirit and energy," she says. "I'm really gentle, and so I like a boy who will treat me that way."
The sexy Transformers
star also protests that she's not the hell-raiser that everyone perceives her as. "I was never a bad girl and still not," Fox says. "I challenged authority in school a little bit but nothing like Jennifer. Now I just speak my mind openly. That's who I am."