Perfect proposal right here.

Take your girl to a nice restaurant.

Get the band to play your song.

Let her order whatever she wants.

When the food comes turn your cap backwards. Did I forget to add that you should be wearing a cap? Well you should be.

As they set the food down stand up and, in front of the whole restaurant, scream "I CHOOSE YOU!" while simultaneously throwing a pokeball with the ring in it as hard as you can at her.

What happens next really depends on the ring in the thing you just smashed into the side of her head. :/