The others are right. The way I see it, if she completely blanks you right from the offset the only thing you can do is say nothing and walk away to talk to girls with some actual personality. Personally, I test them first, just to see if they're really bitchy or if this is just something they do to get rid of guys they don't think can handle them.
Now, most girls who have been like this with me at first, would smile and call me an asshole (or similar) after I said "that doesnt work on me". That's all it took, and they seemed to like it. However, if they were still giving me the "whatever" SPAM afterwards, and their body language hadn't changed, I got moving. This is crucial, cos if she thinks she's hot shit, you need to show her you're not gonna stand for that kinda crap just because she's hot. You gotta have values.
Honestly, if she doesn't respond to a little bit of confident persistence, don't waste your time. I don't care how thought provoking or awesome anything you might be able to say to get her attention is at this stage. Nomatter what you could possibly come up with to diffuse a bitch shield at this point, it won't work, because you're unwittingly falling into an invisible trap.
The reason for this is because it isn't like a shit test you just plow through. When a girl completely blanks you, and you keep firing comments at her even though she's obviously not cooled off any, it stops looking like confidence and starts to come across as needy. You're basically trying to prove you're worth her time and attention, and that shit isn't gonna fly. Seriously, nomatter how cool and confident you are, you're still gonna look like a douche.
So remember, you haven't got shit to prove to this girl and you can't reward her for bitchy behaviour. Show her who's boss and walk away. Interestingly, any times I've done this, things worked out pretty well. You know that thing where you're talking to a girl and you kinda just drift off and she just happens to bump into you again later in the night? Yeah, that happened. Almost every time, and I'm not shitting you.
So yeah, at first you need to show her that you're not falling for her little act. If she keeps it up after that point, walk away immediately. Because anything you say to her past that point is just gonna come across as if you value her time and attention more than your own. It changes from "I'm willing to take some shit cos I know you don't mean it" to "I'm willing to take shit for as long as is necessary cos I really want you".
I've been told first hand by a couple of girls, if they blank you, it's sometimes a test and sometimes not. I can't remember word for word but it went along the lines of, "it's ok to be a little persistent cos it's good to see a guy with some balls, but if they can't take a hint it's fucking annoying and I might even make a scene if he was just wasn't getting it."
So, quick recap. Test them. If there's no change, walk away. And when they approach you later, do as you wish. Oh yeah, and have fun.
