Scripted pickup lines are for losers, and all they'll get you is an eye roll.
I love when I see other guys buy drinks for women...use that as your in to strike up a conversation. Basically tell them you're not buying them a drink, but they will be talking to you anways.
And from there, it's just a matter of charming them with your keen sense of humor.
This guy gets it. You don't say that in a ##### way, you say it in a very confident lighthearted way with a :wrysmile:
She will be caught a little off guard, but will be impressed and intrigued with the confidence. To keep the conversation going and add some humor with that initial confidence say something like "actually you should probably buy me a drink...and after we hit it off, I'll pay you back with one"