Lucy couldn't help but overhear Mr. Jones' dog knotting her sister Jeff. Since Jeff's accident she had the limbs and reproductive system of a pure bred Samoyed and was making some extra allowance on the side as a regionally prized breeder. Lucy felt more than a little envious that her sister was making so much extra money, especially if Jeff didn't have the hands to really make use of the extra money she was making. Lucy knew that was a little unfair to her older sister because maybe the extra cash would one day help Jeff afford more human prosthetics than her current (so fluffy) doggy legs.
Lucy used Jeff's (quite pleasurable sounding) distraction to ransack her room a bit in search of bit of extra cash for a froyo or salon trip. Sitting down at Jeff's computer Lucy found it still in the Chronivac app just as Jeff had left it in making herself a dog girl. It didn't take long for Lucy to familiarize herself with the Chronivac, and tested it by aging herself up just gently past 18 and expanding her breasts a bit. She thought again to how envious she was of Jeff's extra income and decided that a few dog features wouldn't hurt if they could make a bit of money. She didn't want to go full breeder like her sister, so instead decided to be more of a stud. She gave herself a canine penis of the same breed, since it seemed an expensive breed. She didn't want to be so drastically a dog so she stuck with simpler dog features: the extra nipples sounded fun, and so did a tail, dog ears, and a more dog-like nose/snout.
Soon after Lucy activated the changes she took a deep breath and was surprised at first how much Jeff's room smelled like a bitch in heat. Her doggy dick was instantly erect under her skirt as her brain caught up to her nose and realized it shouldn't have been a surprise that her sister's room smelled like her brood-bitch of a sister.
Before Lucy could think what to do about the tent in her skirt, her family's dog wandered in and growled at the extra male competition. She growled back at her dog, as it seemed the only thing to do in response, and he wandered back off whining.
Jeff wandered in apparently at the sound of the whining dog, stared at Lucy's bulge in her skirt for a bit and then finally made eye contact and said, "Oh, mom's looking for you Lucy, I'll go fetch her."
Lucy felt like she didn't even have time to react before Jeff burst with speed back out her bedroom door. Lucy did have time to wonder though if the way Jeff had turned around and just about presented her pussy to Lucy and the way Jeff's hips had shook a bit on the way out were deliberate teases or not.
Lucy's mom walked in and to Lucy's embarrassment, Lucy's mom's eyes also seemed drawn immediately to Lucy's puppy penis doing it's best impression of a circus tent with her skirt.