Hey guys. I've been playing with this routine about a month now, and it has not failed me yet. The routine takes 3 seconds with lots of build up. It's really dumb, which makes it fun. It helps break the ice early in set. I have an iPhone. Guessing it works with other phones fine too. The main part of this is the build up.
Tell her you're going to show her a magic trick and it's gonna blow her mind. Check in and make sure she is ready, then hold up your iPhone so she can see the screen. Wave your other hand over it then hit the top button so the screen goes from being off to on.
Then, look at her and nod proudly and say "Right?" The. Wave your hand down and turn the screen off.
Note: the point is not to impress her with magic. It's to be fun and playful. If you really push it, she will enjoy it. You can easily do this in front of mixed groups too. You're letting everyone have fun at your expense, which lightens the mood, stops guys seeing as a threat, makes you appear more self-confident (a guy who isn't confident wouldn't do a magic trick that dumb), and makes you leader of the group because you are commanding everyone's attention.
Try it and let me know how it goes for you.