The watch was set to 5pm, one hour off. You decide to set it to the appropriate time of 6pm. After setting it you looked up to see that Jamie was tugging at her clothes and adjusting her bra a lot. In fact all her clothes appeared a little too tight on her body, at least from behind. She turned around and approached you with a grimace on her face. "Hey, do my clothes look like they shrunk-" she suddenly went wide eyed. "Did you shrink too!?"
"No way! You're definitely taller though, I’m surprised I didn't notice it sooner." You thought that her recent growth spurt was kind to her, but she was growing faster than you thought. She normally came up to your shoulder but now the top of her head came to your nose. Her breasts looked bigger too straining against her shirt like they were trying to escape.
"Really!? Let me see!" She ran out of the room and over to the Measuring rod of her bedroom.
"Can you check for me?" You strolled into the kitchen and picked up the tape measurer. You pulled the tape and checked it next to Jamie.
"5'3, looks like you've grown another 3 inches little sis."
"Ha, I'm hardly little now, that means I'm only 1 inch shorter than you now!" She stuck her tongue out and started dancing about the hallway.
"Yeah sure, I'm not done growing yet either so don't get your hopes up." As much as you just tried to shoot down her dream, part of you was getting strangely aroused at the thought. And what brought on her suddenly growth anyways? She looked like one of the well-endowed younger classmen at your high school now, not just your little sister. She had to be at least 13 or 14 now not 12. Was it the watch that did it? You had to check but you couldn't do it so quickly, if the watch WAS really doing this then your sister or someone else could catch on if you weren't careful. You'd have to test it on someone else too or wait til tonight when Jamie was asleep...