Is it politely to say

Do not even look at me.
(That's today's Norm)

It’s a nice opener as a way to flirt. I’ve used it many times successfully.

The third is the most polite, but tone and approach can make a huge difference. My best friend says which a huge, warm smile, "Hi ! Do we know each other ?" Most people seem to wish the answer was "yes !". 😅