The attitude a girl gets when her looks are only a 7 out of 10, but she gets hit on all the time because guys are intimidated by the much more beautiful 8's, 9's, or 10's - so she has a super inflated ego and unrealistic view of her own beauty.
A girl who thinks she is far more attractive than she really is since she gets hit on disproportionately because guys are afraid of rejection from the more attractive women.
Derek "Whats up with that girl at the bar, she isn't even that pretty but she wouldn't talk to me?"
Mark "Oh, her. Yeah, she has the seven complex. It made her a total bitch. You're better off hitting on her pretty friends."
Since it was last call I was going to settle for that semi-attractive girl to go home with, but then I realized she had the seven complex so it wasn't worth my time.