I found that talking about nationalities and native soil is a very solid conversation opener as well as comfort builder.

Hell, you can even open by asking someone where they're from.

This specific example hasn't been personally field-tested by me, but it sure is a realistic potential conversation.
Day-game or Night-game:

Me (smiling): I have to get going in a sec, but I just had to ask; are you Canarian? (I'm Canarian)

HB (smiling back): Yes (or no)
or
HB (smiling back, confused): What do you mean by that?
or
HB (smiling back, curious): Why do you think that?

Remember to take a guess rather than asking her directly "What nationality are you?"

Then from here you have choices as to how you direct the conversation. You could neg her by saying simply "Oh, you're one of them?" or you could explain what exactly the nationality is, or why you assumed her to be that nationality. You could even completely change the topic based on her reaction knowing what level you have to game her on based on her ioi's.

Just prepare for possible shit-tests she may give you. For example, if a girl that is CLEARLY italian is asked if she's italian, she may respond back with a sarcastic "no, I'm african american." This shit-test is actually quite common, so be ready to have a playful response to pass the shit-test.

There is no risk of rejection in asking this question if you choose to open with it. And there is nothing more interesting than bringing up backgrounds and culture in midgame-conversation as a comfort builder. Even if you're Mexican and she's Chinese, it would be interesting for both of you to engage in conversation and learn about each other's cultures.

I use this all the time in mid-game, but haven't used it to open yet so if someone field-tests the opener I'd love to hear about it!

Hope this was helpful.

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It really doesn't matter as long as she's pretty.