You burst out into the hall, hands ready in a karate pose, but the only thing that surprises you is your bouncing breasts because honestly, having been a guy before and not having bothered to put on any of the many frilly undergarments in the bureau drawer, you have absolutely no support.
The sound, however, comes again. It sounds like someone laughing at you. Snickering even. And it's from the room across the hall, the door slightly ajar.
You go and push that open, seeing that the sound has come from a mechanical monkey windup toy sitting atop the dresser in a very old-fashioned Victorian nursery. There are toys all over the room in fact, and it's obviously a little boy's playroom, as evidenced by the lack of dolls and various pink frilly things you might expect with them. Instead, there's toy soldiers, trains, wind up toys, a rocking horse and so forth...along with a mirror over the dresser.
You catch a glimpse of yourself, and the buxom raven-haired beauty in your guy's clothes blurs and you suddenly find yourself shrinking. You grab you belt to keep your pants from falling off and feel the return of your cock and balls, after a fashion, since you're looking back in the mirror at a little freckle-faced red-haired boy not more than seven years old.
The monkey grins and makes mechanical snickers.