Shortened form of Stefanie given to glib, usually incredibly hot, chicks who like to feign interest in only the most recent causes celebres. Stevis are characterized by irascibility, impracticality, lack of imagination or original thought and a penchant for banging dudes with little or no persuasion.
Jill: Ya, Brenda
's hanging out with her new friend Sage again this weekend.
Chris: Really? She just met him three days ago at the organic farmer's market. She's supposed to have dinner and drinks with us!
Jill: 'Fraid so; they're going to picket the local Army recruiter's office on Saturday.
Chris: Wow, she's turning into a real Stevi.