As he wandered around the mall, Jim heard a rude laugh and saw a big, well-muscled boy shove some smaller kids aside as he strode through them. Kyle, a member fo the high school football team and a real bully. He usually had a couple of other rough jocks from school with him, but was alone today.
Jim grinned. He wouldn't be a bully without all those muscles. And maybe a few years, too. He blew the balloon up and concentrated. Could he shrink Kyle back to a point where he wasn't muscular? Yeah! Younger. He started letting air out of the balloon.
SSSSSSSSSS. Kyle didn't change all that much at first, but a faint mustache and goatee he had been working on vanished. Then he stumbled as he started to get smaller. He must have worked on bodybuilding a long time, for even when he was obviously younger, he still looked buff.
SSSSSSSSSS. Kyle stumbled again, this time walking right out of his shoes. And his shorts fell down to his knees, though his tent-like shirt hung low enough to keep things decent. "Huh? What's happening!?" Kyle's voice cracked as he went back through puberty in reverse.
SSSSSSSSS. Jim grinned at the now 12 year-old and kept letting air out. 9, 8, 7... He stopped when Kyle looked to be about 5 years old, confused and scared. "That's good enough. Release."
Kyle kicked away his pants and started sucking his thumb, crying. "Where's my mommy?"