You don't care what you are, so long as you're not a stupid tooth fairy, so you spin the rings at random. You feel a slight shift, and look yourself over.
You're mostly the same, but your outfit's a little different; your tutu is gone and you're simply wearing a leotard, a two-tone leotard that starts out blue and smoothly fades to pink. Your gloves and diadem have just disappeared. Your wand's changed as well; the star at the tip has become a symbol that appears to be a combination of the scientific male and female symbols, with the external bits sharing the same ring.
Looking at the wand, you realize what you are. You're a sex-change fairy. You can make men into women and vice-versa, but more than that, you can change their bodies to fit their new gender, making them younger or prettier, or even going so far as to, say, turn a guy into an anime-style catgirl. You can even change their thought patterns to match their new gender in any degree; about the one thing you can't change is their memories (not that you'd want to.)
Yeah, you think. Yeah, why not? You had to change gender to take this job, didn't you? It's high time other people shared in the experience. Look out, world, you think, here comes the Sex Change Fairy! Six inches tall and full of potential mischief, you flit out the window.