Not exactly a line but years ago a car came up the inside lane beside me on the M3 holding up a bit of paper with 'coffee?' written on it. I shook my head, he dropped back and later re-appeared with 'your loss' written on it. A great memory.
not really a chat up line but in my local chemist was a young lady wearing a T shirt with "get your coat you've pulled" written on it. When she got to the counter she asked for a much advertised treatment for thrush.
I was already chatting to a young lady when I used a line from Rik Mayall in 'Bottom'
"Hmm you smell lovely, do you use Timotei?"
It did break the ice and her reply was "No, its all natural"