Karyn, seeing her friend feels a pang of guilt. While she had no role in causing Jon to become ten again, it was her sense of mischief at caused him to look like a schoolgirl. And for that reason, she knew she couldn't go comfort him; he'd think she was after the stone, and 'finish' off his road to girlhood.
"Its not okay' Jon said, fighting the urge to sob. "I'm a little kid. And girly looking one. I'm looking like a mini you!" He looked down for the stone, and saw that it rolled backwards, towards a door. He groaned, as that door opened and his little brother Mikey walked in. His first reaction was to smirk. His second was to pick up the stone.
"Jon. You look cute like that" he smirked. "I never knew you wanted to dress like a girl. I wish..."