Dude. You're obviously obsessed with this girl. Just make a plan as to what you're going to say, and next time you see her just act totally wierded out and start laughing and start talking to her. In fact, go ahead and make the joke about her stalking you. The longer it goes on the weirder it will be, so just figure out what you're going to say (something like "ok this is just too weird, I keep running into you places, I'm techboyjk... are you following me??) and then try to turn that into a conversation and then try to turn that into finding out where she's from (oh my god, you're from florida too?) and then voila with a little luck you'll turn it into dinner. If not then, then you'll at least know her name the next time you run into her and you can laugh and say hi to her wherever, and eventually you'll work it into something.
