This one I really like, and use on pretty much every first date over the last few years.

So, you both have just got your drinks, and as you cheers, look at her in the eyes. 90% of the time she won't look at you, and this is how you proceed:

You: you didn't look me in the eyes (kinda playful/shocked look) Her: Ya, so? You: I've heard it's seven years bad sex if you don't..

Say it in whatever way it comes off as cool, not creepy.

I was in Paris and had a girl say this to me. You can tell a little story before or after you get a reaction, about how you were traveling in Europe, or you lived there... Whatever, and this is how they do it.

At this point you will have got a reaction from her. This is great: If she says something like "Omg, that'd be terrible" "Haha, where did you hear that" etc etc. Basically, if she acknowledges that statement you know the chick is DTF/more open to the idea. I have yet to be on a date with a chick who said "That'd be soo bad" in a playful/serious way, and not take it down first night.

Keep in mind, sometimes a girl will just not acknowledge it... These girls obviously will require a little more effort, and may not be as fun.

To add, even if she does look you in the eyes (This is more common in Europe, than NA, and now that I think of it work better on girls in NA) you're still good because you can playfully ask why she does that... Hopefully she'll say the same thing you were going to, and even if it's different, you still get a reaction when you explain the superstition behind why you looked her in the eyes.

Now, later in the evening when you cheers again for whatever reason, if she makes a point to look you in the eyes, it's fucking on.

Note: This may be out of some of your comfort zones to start off as aggressive, but if you can pull it off, I highly recommend it. It doesn't even have to be a line like that, but anyway you can casually transition into a more sexual conversation, do it. For example, you get to talking about traveling, and you bring up how you were in Greece and there was a nude beach. .. Now you can discuss if she'd ever been to/ would go to one, how some chicks just shouldn't be naked, and laugh... etc etc.. Anyway, I think I've made my point. If there is anything I can elaborate on, let me know.

Edit: When you cheers her later and get the look in the eyes, throw in a wink for good measure.(Exactly what this french broad did...Really made me want to fuck her)