Tammy, having eaten her fill of the leftover fast-food, decided to spend some time jumping rope to burn off the calories she had just taken in. After retrieving her rope from her bedroom, she heads outside so her exercise won't disturb the other people in the dorm. As Tammy started her workout she felt her body begin to heat up faster than normal. The athlete ignored the abnormality, deciding it must be because she was still pretty fresh off her jog.
Unbeknownst to Tammy, who had closed her eyes to focus, the mutation liquid was already having an effect on her, her muscles visibly growing with each slap of the rope. The growth brought a sense of euphoria to Tammy, it felt better than any other workout she had ever done. Lost in what she thought was an especially powerful workout high, Tammy didn't notice that her rope was no longer hitting the ground as she swung it, her height increasing alongside her muscles. Even when her clothing gave way to her growth she continued, the intense heat generated by her body counteracting the chilly evening air. After thirty minutes the woman went from having the lithe muscles of an athlete to body-builder like proportions. The now nine foot tall amazonian woman still completely oblivious to her still-growing form.
It was at this time that further changes began to manifest. Her clit began to engorge, slowly forming into the distinct shape of a penis. A developing ballsack quickly followed, sending a flood of hormones into her body. As her new genitalia continue to grow, the sensations of her workout rapidly turned into lustful ministrations. Her cock and pussy both tingling with excitement with every pulse of growth. A few minutes after her cock and balls appeared, growths appeared between her shoulder blades and on her tailbone. The one between her shoulders pressed out into the distinct shape of a shark fin, while the other one stretched her spine out behind her, eventually ending in the caudal fins of a shark tail. The skin on both her dorsal fin and shark tail thickened and took on a blue-black colour.
It was when her jump rope struck her tail that Tammy snapped out of her trance. The woman looked down at her mutated body in shock, unable to comprehend how much she had changed without noticing. She had stopped at a massive eleven feet tall, her head now level with the second story windows of the dorm. Her arms and legs were thick as tree trunks, her old body would have been bar to wrap her arms around anything but the narrowest parts of them. Most shocking though was her cock, matching her limbs in thickness while dragging nearly to the ground, with balls so big they had nested in behind her knees. Luckily her breasts had also grown, though not nearly as drastically as the rest of her, and were still easily noticeable despite her bulging pectorals.
Once the initial shock of her transformation faded, Tammy realized that even if no one had witnessed what had just happened, all it would take was someone looking out their window for her to be seen and reported to the police. Options raced through her mind about what she should do. She could look into her window and see if any of her roommates could help her. She could also run off into the nearby woods and try to hide herself while she masturbates. As she contemplated her options, her throbbing member and dripping pussy presented another: just go with the flow, find someone to relieve herself with, unconcerned with the victims fate.