Disqualification and Teasing
Use these lines fairly early, so you don't come across as a guy who's dying to sleep with her. The idea isn't to offend her, but to create the impression that you're not chasing after her. Making mistakes when you're having fun and being bold is much safer than when you're serious. Some disqualifiers are ambiguous, so be careful not to come off as an insulting jerk.
If she's short:
I can't hear what you're saying from down there
Is she always like this?
You have beautiful eyes... Can I touch them?
You talk too much.
If she's not talking:
You talk too much! or Are you ever going to shut up?
You have broad, manly shoulders.
There is definitely nothing going to happen between us.
You're fired.
You're way too much of a good girl for me.
I'm not boyfriend material, not at all. That guy over there looks good for you.
We're breaking up. I want my CDs back.
You know what? You're either the coolest person I've ever met or the worst. I'm not sure. I'm curious to find out who you are.