What is the best introductory flirting you've witnessed from someone?

By best, I mean that it reeled someone in, completely wanting the flirt for more than just superficial reasons regardless of what the flirted actually wanted.

By introductory, I mean that they just met for the first time. Describe what happened.

I'm looking for personal real life examples but if you don't think you have any good ones, it could be from TV too. It could also be something you've said or done or something someone has said or done to you.
What is the best introductory flirting you've witnessed from someone?
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