Terra slipped on the ring, which suddenly fit perfectly. She noticed that the topw of the ring, inscribed with the symbols for 'amle' and 'female' in a yin-yang thing, was actually a sort of knob. Idly, she twisted it - and yelled as a strange feeling hit her.
She felt for the oddness in her pants - and found a penis. Instinctively, she clutched her chest, and the tiny AA-cup breasts which had been her pride and joy since they appeared last month were gone, her training bra empty.
She flipped the ring back - and her bra filled up and her panties were empty.
She picked out a couple more objects, looking for ones with moving parts like her ring - she figured that those would be the 'safe' ones that could be controlled. The rest she put in the box and put it up in her closet - no way was she going to risk a permanent change.
Terra stripped naked and twisted the knob again and watched her body change from girl to boy. Terra's first sight of male genitals was arousing, as were the sensations as he fondled them. Watching his new cock grow, he rubbed it and squeezed it, and soon found out what way it felt best. His hand continued to pump until an orgasm erupted and sperm sprayed out.
Terra was fascinated with the sight of his cock erupting, and licked his hand clean, savoring the taste. Twisting the ring, Terra was a girl again, and promptly fell on the bed and began masturbating with her sperm-covered hand until she climaxed. At heart, she was still a girl, even with a male body, and the sight of an erupting cock made her horny beyond comprehension.
She panted afterward, then looked at her hand. Could she get pregnant if one of her own sperm found it's way to her egg? Was that incest, getting your self pregnant?
Terra shoved that thought aside as too scary and looked at another piece of jewelry - a charm bracelt with a drawstring bag. The bracelet, she found, had the words 'Happy Birthday' worked into the knots of the chain. In the bag were twenty beads - five large gold, five small gold, five large green and five small green.