Trust me on this, don't try some super secret ninja way of finding out her name. If she catches you doing it, or you mess it up and call her the wrong thing (I've seen it done before), you will look like a world class dork. If you are a funny guy, try and make a joke out of it, she'll think you're funny and you've got the balls to admit you are a dumbass (you are, really, but it's ok

)
Remember the secret of confidence is that no matter what you do, you're not uncomfortable doing it. The more embarassing the thing is, the more confident you seem if you can pull it off without loosing your cool.