I could never actually use a bonafide pick-up line, and so have never given the matter any real thought. Though back in December, when I was between girlfriends, I happened to pass the most beautiful brunette in the hallway at my university. I just stopped her, and I said "excuse me, but do you ever have that, where you walk past someone, and they're so attractive, that you just refuse to let them walk past you again and out of your life forever? Well, it's just happened for me." It was bold and completely genuine, and it really seemed to work - we went out for dinner that same night. So I think spontaniety is really important.
As for other, corny, done-to-death pick-up lines; well, they're what internet geeks think up in their spare time and shamelessly distribute over their MSN lists at 1am on a Friday night
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