You stop at the hotdog stand and notice the man does not only sell hotdogs - he also sells a variety of sweets. Particularly of interest is the small mouse-shaped sugar candy, always your favorite. You buy a bag of them and start chewing away at the soft but sugary goods. As you are eating the bright white candy, you start getting itchy beneath your clothes but you think nothing of it. For a while, this itching builds up but you are too engaged in eating the little sweets. Until your feet start hurting tremendously.
Absently-minded, you take off your shoes to see what's causing the pain and are surprised to find your feet longer, thinner and a lot hairier than before - and your toenails are HUGE! You finally start noticing that the same thing has happened to your hands, and that the itching was caused by a bright white fluff that is now all over your body. It couldn't be long before it happened - a whole coat of white fur floomps up from beneath your shirt, making things really tight.
Now being unable to stand straight on your realigned legs, you go to a somewhat bent, squatting position as your legs are now arm length and much thicker. You feel a tremble cracking through your spine which ends in a sort of wobbly feeling near your butt, something poking against the back of your pants and seconds later a thin, long, hairless pink tail squirming out of the left leg of your pants.
You try to scream in shock, but all you can produce is a loud "SQUEEEK!" and a quick feel with your pawlike hands reveals that your head has changed as well in the meantime, and you can grab one of your ears and look at it. You try to move, but your clothes are severely in the way, and you almost trip over them as they seem to be growing fast...or are you shrinking? The latter seems the case as within no time you try to find your way out of your clothing.
Finally, managing to do so eventually brings you to the bag of candy mice that you dropped earlier, the sweets now seeming lifesize. Without thinking you immediately climb upon one of them and start nibbling away, 'cause if there's one thing a mouse loves it's sugar...