"Sam? Sam, sweetie?" Karen wiped the water from her eyes to see her daughter struggling against her own growing penis. "Sam, you...you, too…" She peeled her blouse away, tossing it to the ground and letting the sun play over her wet skin. Her tail flicked and her cock began rising again. "I know what you need, darling. You need to resist it."
Sam gripped the base of her cock tightly through her pants. Maybe if she squeezed it tight enough that would stop anything else from spurting out. She watched as Jennifer and Jack also began stripping out of their soaked clothes.
"You need to resist it and you need to feel it bloom and grow, don't you?" Karen took hold of her own shaft. "You need to feel it flood through you," she said as she began stroking her rat prick. She was already leaking precum that lubricated her masturbation. Her teeth were beginning to grow now and her face was beginning to grow into a slight muzzle. A whisker sprouted above her upper lip, then another, then more as a thin tuft of fur began sprouting between her breasts. "Feel it ache for release and swell and burst out of you in an explosion of cum!" She leaned her head back and closed her eyes as she practically screamed the last word and semen spurted from her cock in thick gouts that traveled nearly ten feet.
Samantha bit her lip and groaned as she watched her mother jerk off her rat prick and begin turning even more animalistic. Her own balls ached and swelled with a need for release. She took a deep breath and closed her eyes, muttering to herself for distraction. If she could focus her mind somewhere else, maybe she could keep from making it worse, keep from going down the same road as her family. "Prime numbers. Two, three, five, seven, eleven, thirteen..."
"That," Karen exclaimed, "was good!" She sniffed at her fingers before licking and then sucking them clean of her semen. "Don't know why I was resisting this. I…" She discarded her bra, baring her breasts to the sunlight. "I feel amazing!" She approached Jennifer with a glint in her eyes. "It all makes sense now, Jen, don't you see?"
"...Seventeen, nineteen, twenty-three, twenty-seven...no, I mean...twenty-nine. Nnggghhh…" Samantha continued trying to distract herself from her throbbing dick. She was shuffling her legs, trying to keep the sensitive head from rubbing too much against the fabric. She thought she could hear a siren in the distance. Help? Maybe she could hold out for it. "Thirty-one, thirty fi--uh...seven, forty-one…"
Jennifer's shirt and bra fell to the ground with a wet splat. She shivered for a moment, but then Karen was up against her, one clawed hand reaching around to grope at her chest and the other reaching around to grab her bestial cock. She moaned softly as she grew hard again and felt the shaft of her sister's dick pressing against her, sandwiching itself between her buttcheeks and sliding against her pussy. "It feels so good, Jen. If you don't let it happen, you won't be resisting something terrible. You'll be denying yourself something wonderful! Look, Jack thinks it's wonderful too."
"HAWWW!" Jack had stripped clothes away as well. He brayed as he watched Karen fondle his wife. He watched the two, mesmerized. He couldn't pull his eyes away from Jen's equine endowment. His nipples, hard from the cold water, began visibly enlarging as his areolas widened and puffed. He rubbed at them with one hand, while the other went south. His cock was still there and was erect, but it had diminished significantly in size along with his balls, now only a couple of inches long and seeping precum as he worked it with his fingers. He rubbed his legs together, moaning as hairs began sprouting on his groin, thickening into bristly cream-colored fur that crept up his belly and reddish brown fur as it spread over his ass. His hand went lower, disappearing between his thickening thighs. Jen and Karen watched him eagerly as he worked his hand in and out with a series of wet schlicks, a look of intensity on his face. "Jennifer...god, I'm so horny...hard...empty...Just need to...HAWWW-HEEE! HAWWW!"
His eyes opened wide and his face grew out into a partial donkey snout, the loud bray rolling from his chest as his dick spurted one stream after another of thin ineffectual semen. His thighs clamped down around his hand and he shuddered in orgasm as a more viscous fluid streamed down his thighs.
Watching Jack bring himself off and advance further into beasthood made Jennifer's cock grow almost painfully hard. She pressed back against Karen as her sister purposefully stroked her cock. It didn't matter right now that it was her sister. It didn't matter right now that they were becoming animals. All that mattered were the hand pumping her cum-slicked donkey dick, the need for release building in her heavy ballsack, and the irresistible scent wafting over from her husband's loins. She brayed in response to her husband's display as a donkey tail sprouted almost explosively from the base of her spine accompanied by bristly gray fur of her own sprouting over her ass, down her legs, and up her back. Her belly clenched and her massive member expelled another heavy load, sending streams of cum slinging wildly over the patio as Karen jerked her off with abandon.
"Fifty-seven. Fifty-nine. Sixty-one. Mmm, fuuuuuck!" Samantha opened her eyes just in time to see her aunt Jennifer come like a firehose from her own mother's ministrations. It was too much. Her hand immediately slid down to rub the head of her own cock and it let loose with a torrent of cum that sprayed through her jeans. She fell to her knees in the grass moaning in a haze of lust as the spasms in her dick slowly calmed. She fell over onto her back, panting, chest heaving, mind turning to swiss cheese, seeing stars as the last few drops of cum oozed from her wilting member and the sound of sirens approached.