It's been my experience that women don't drop pick up lines so much as create openings for pick up lines.
Example (and it should be noted that this is a gamer girl): I was playing with my normal group of gamer friends at college at the library, and a gamer girl I know who never hangs out with that particular group shows up to say hi. I'm playing the Americans in a game of Axis & Allies. She grabs one of my transports and starts playing around with it, moving it around the map, finally ending with the transport at Brazil.
Me (picking up on the opening for once in my life): "Say, speaking of which, Brazil is playing at the student Union tonight. Wanna go see it?"
I gotta say though, with my wife, it was totally a facial expression thing that let me know she was interested.