"...the red-headed boy my age dressed in rags," you say. You don't know why, since from his clothes he looks like he has a harder life than many of the other options, but for some reason you feel drawn to him. The medium just smiles.
Suddenly, you feel a wave of disorientation, and you are blinded with a bright light. When it finally dies down after a moment, you look around and find yourself in what seems to be some sort of alley between buildings, though you can't see for sure or make out exactly what the buildings are because it's very dark. You look up and see a full moon and far more stars than you can usually see in your area, providing just enough light to see in what is apparently the middle of the night. You look down, and see different clothes, and a different body. Instead of wearing jeans and a T-shirt, you are wearing the same rags that the boy in the mirror was wearing, made of coarse, scratchy, dirty, worn fabric. Your build seems to have gotten lankier and skinnier. You feel your abdomen through the rags you're wearing--yep, you're definitely more slender. The slightly paunch you had has been replaced... mostly by skin and bones, though there's a thin layer of lean, wiry muscle there that you think you can feel all over your new body now that you've noticed it. You aren't wearing any shoes, and you can feel the dirty, damp ground beneath your feet.
On the ground, you can also see a puddle of what you seriously hope is water, so you go over and kneel down (not worrying about getting your rags any dirtier) to take a look at your new reflection. Your new face is an even bigger surprise than your new body, even though you already saw it in the medium's mirror. If anything, already being familiar with it just makes it a bigger shock to see it moving as you move and making the same expressions that you make. Your face is still that of a teenager, but basically everything else is different. Your hair is bright red, long and unkempt, and your eyes are light blue, completely unlike... whatever they were before. You can't seem to recall exactly what colors your eyes and hair normally are, or were, but it probably isn't important. The darkness makes it hard to tell, but your skin seems to be paler--you would guess that it is, since you can still make out a scattering of freckles. Your features are coarse, your ears stick out, your nose is turned up, and your brow is heavy. You have buck teeth, and after seeing it in your reflection you realize that you've been leaving your mouth hanging open this whole time. Your new face is definitely homely, and though it may just be a trick of the light, or lack thereof, it gives you the impression of someone who isn't too bright.
You continue staring at your reflection, and then frown and furrow your heavy brow as you suddenly feel thoughts entering your head. Memories. Staring at your new face has started to make it seem... not so new anymore. You are starting to remember this life, starting to realize where you are, when you are, and who you are.