The stone glowed, granting Karisma's wish, but a split second before the wish was granted, the word "man" was replaced with "woman", causing Jon to become a black woman named Joanna. But that wasn't the only thing different. Karisma also wished that they would love each other just the same as always, so now both Karisma and Joanna were lesbians. Married lesbians.
After the stone glowed, Karisma gasped. She was no longer pregnant! After all, a woman having sex with another woman wouldn't get anyone knocked up.
She didn't clearly remember the wishing stone from before (when Jon showed it to her at school), but on some level she knew that her wish had come true, but what had happened to her pregnancy? That wasn't part of her wish.
Karisma heard her own wish, so her memories hadn't changed to fit the new reality. But since the stone had made her a lesbian, she'd soon discover that she was attracted to females instead of males. How would she react to that?
Meanwhile, the twenty-something black lesbian version of Jon (now named Joanna) was ...