Jake spent a few seconds rubbing his tail, feeling every new sensation it had to offer. The scales were smoother than he originally thought, and the fact that it was an extension of his spine sent chills through his body. He wanted more of that feeling. Jake dragged his tail back to the desk to make some adjustments.
Jake decided to make his new tail a good six feet. He also added his tail would be more prehensile, so it won't get in the way of doors or anything. As an added bonus, he could use it as a third arm. "Oh god, this is exciting!" Jake said wagging his tail in anticipation.
Jake waited, and the changes started kicking in. Right away, he could see the base of his tail extend, with more scales covering his skin. "Oh yeah, there it is..." He said, rubbing his growing tail as scales cover inch by inch. "Oh! What the?" Jake started feeling something different from the first growth. His spine from the inside started cracking, making room for new muscles. "It hurts... But it feels good..." Jake could hear his cracking bones as his tail grew 1 foot taller than last time.
The pain was getting to him, that Jake started grunting. His tail was another few inches longer before he started to take control of more muscles in his spinal cord. His tail started whipping and lashing, as Jake's spine could now support the weight to lift it. "Ahh... Almost there..." Jake was panting as he fell to his knees. His tail shot out the final inches of his growth, causing him to jerk backwards. "Gah! YES!" Jake stood up on his knees as the growth ended, and he fell to his back.
Lying down, with his tail underneath, he tried controlling it from his current position. He lifted it between his legs and started poking his chest with it. Jake smiled as he saw his tail was not only longer, but now fully functional like a third arm. Jake finally stood up, whipping his tail around to get used to the new muscles in his body. "This is amazing!" Jake exclaimed as he started lifting things with his tail. It was surprisingly strong for a newly grown limb.
Jake saved his changes to his profile and turned on reality alteration. He was in awe seeing his giant gator tail wag like a dog's. "I gotta show this to Leon! We could have so much fun with this thing!" Jake started to ponder on what to do next.