Melissa pulled Erika along by the hand, unaware that her girlfriend was discreetly adjusting her skirt over the bulge of her semi-flaccid penis. Erika realized her palms were quite sweaty, perhaps even sticky from having touched herself in the car, and hoped her friend wouldn't notice.
As she walked through the front door, a sudden pain in her bowels forced her to stop for a second, letting go of Melissa's hand and leaning against the doorframe.
"What's wrong?" Melissa asked with a worried frown.
"I... I don't know, it's my stomach I think..." Erika speculated, unsure. Her temples were pounding with the beat of her bloodstream, and she was definitively sweating.
Another sharp pain almost had her on her knees, whimpering. She felt hot and uncomfortable, shivering all over.
"I think I need to use the loo... I'll be right back", Erika said as she staggered towards the bathroom. "I must have drank too much of Melissa's milk", she thought to herself, closing the door behind her.
A strong spasm had her wince and she dropped her bag to let herself fall on all four, too weak on her feet.
She heard the sound of fabric tearing and a seam cracked near her hip, revealing the white of her panties underneath. Almost simultaneously, her bra strap gave out under her ribcage, slapping loose and letting her breasts bounce freely under her shirt.
"WHAaat is happening to me?" Erika whimpered in a hoarse voice between two hiccups. Were her clothes shrinking?
She crawled around to sit on her ass and forcefully removed her shoes. Her toes were hurting badly... In fact, her feet seemed a little bigger than before!
That's it, Erika realized, she was going through another growth spurt - and this time it was happening fast. Melissa's milk was probably filled with growth hormones. She could feel her body had grown a bit taller and become a little more toned as well.
A slight pressure in her underwear had her grimace. Lifting her skirt and pulling her penis out of her panties, she noticed a difference in weight. Its size had increased even more than the rest of her body, reaching three inches soft now!
"As if it wasn't annoying enough before!" she thought bitterly.
If she came near Melissa and things started heating up again, she could easily be found out. Melissa had expressed her disgust of boy things enough in the past, and Erika didn't want to risk the relationship.
There was only one solution left, then.
Erika took a deep breath and began slowly stroking her member. She needed to ingest some goo to turn female, at least for the next few hours. She would only have to deal with the increased libido it provoked, and it wouldn't be much worse than her dick's.
At first, her penis didn't respond much to the solicitation. After all, she had cummed more than once in the past few hours already... and it went completely limp with the stomach cramps she just had. But she knew it was always hungry for more. After a minute, she felt it stir pleasantly again while her balls were swelling, filling with goo.
Sliding a hand in her panties, she reached for the space under her balls and pressed it with two fingers, letting out a soft moan. Her penis hardened, becoming meatier by the second. The skin pulled back completely, progressively turning into a canine sheath.
Soon enough pre was leaking down its length, which resembled more and more that of a canine member. Fully erect, it looked even larger than it used to before this growth spurt...
Erika bit her tongue to keep from moaning out loud. She had to hurry and finish this before Melissa would come looking for her. Her imagination started invoking all sorts of scenarios, mixing memories with fantasy. The lewd cries of her friends as she slammed her canine knot into them; the feeling of her throbbing monster filling their bellies with cum.
She closed her eyes, shivering, the two furry orbs she was sitting on churning intensely as they pushed her panties aside and came in contact with the cold tiles. She pressed the spot harder and felt goose bumps all over her body as it tingled pleasurably. Her knot grew wide, the familiar curves of its bumpy shape oddly bringing comfort to Erika.
Her thoughts wandered to the feeling of Max' canine cock into her. He may be smaller, it did feel amazing... Erika's cock buzzed in agreement, a cascade of pre spluttering on her hand. Directing her wet red rocket toward her face, she leaned over, her mouth open, thinking of Max pounding his knot into her as her own erection would swing rythmically under her belly, until both would burst with delicious goo...
Erika felt her balls tighten; a rush of cum fired up her member. Several thick ropes of the liquid landed landed in her mouth, and she gulped as much as she could, holding on to her throbbing cock as firmly as she could to keep its aim. It lasted a full minute, but felt like an eternity.
Sticking out her tongue to the maximum, she licked the slit at the tip of her penis, a low moan escaping her throat. She loved basking in the afterglow. Some canine seed had spattered on her cheeks and more on her chin. Opaque beads had also landed around her, glistening on the tiles.
Barely a few moments had passed and Erika was already on her feet to clean herself, her skirt lifted by the canine member still raised proudly in front of her. Her knot was slowly deflating as her gonads sank in her body, her balls turning into lips. It was working!
Looking at her reflection in the mirror, she stared and blushed. Sure, her huge canine penis sticked out on her feminine frame, but she also looked older and prettier than before. While her cum-stained face retained some innocent traits, her body looked almost like she was fifteen instead of barely twelve. She was finally catching up with her friends who had been exposed to the vial that fell into the pool.
"Are you ok in there Erika?" Melissa asked through the door. "We still need to talk..."
Erika could still feel the taste of mutant goo in her mouth.