You shake your head to try to clear the cobwebs out. "You've done something to my brain, you Goth bitch," you accuse. "I can't believe I was even halfway considering staying as a girl. Make me a guy again right now."
"Fine," says Tamara. "I will make you a guy. But, uh, just FYI, I'm not a bitch. I'm a cunt, in every sense of the word." An evil smile creeps onto her face as she points at you.
You turn back toward the mirror to watch the change. It's not quite what you're expecting, though. A thick carpet of hair begins to sprout from your chest as it expands, even the breasts expanding with it -- and expanding, and expanding, and expanding.
The rest of you is getting bigger, too -- your arms, legs, and even your face is becoming decidedly doughy.
Red pustules appear on your face and upper chest, popping into existence until you have what looks like the world's worst case of acne. Your nose is strangely crooked, there are braces on your teeth, and your short hair looks greasy and has a couple of cowlicks sticking almost straight up. Your image suddenly goes blurry, but then returns into focus when a pair of thick glasses with black plastic frames appears on your face.
"There you go," says Tamara. "You're a guy again, just like you wanted."
You start to yell, "I can't believe you did this --" but it comes out as more of a wheeze, and you're interrupted by a coughing fit.
"Asthma," explains Tamara while you hack. "Or allergies. Or both, probably."
"I must weigh 300 pounds," you say in a whisper so as not to aggravate whatever respiratory problem you're having.
"Don't exaggerate," says Tamara. "You're closer to 280. But don't worry, you've still got some self-control. It's a glandular problem, nothing to do with overeating."
"Come on, you knew what I meant," you groan. "I want to go back to the way I was before I drank that potion."
"Then you should have said that," Tamara says in a mock-offended tone. "All you said was 'make me a guy again right now.' You didn't specify. You have to be specific when it comes to magic."
You sigh, which makes you cough a few times again. Finally you manage to croak, "Do you want me to beg?"
"It'd be nice," says Tamara.
"And I suppose there's no chance of me becoming any better looking than this?"
"Hey, like I said earlier tonight, the world can always use more attractive women," she says. "Now, I think in this reality, you'll find that your parents have a lot less money, mainly due to all your medical bills..."
She trails off. You look at the overweight teenage guy with bad skin in the mirror and contemplate being like this for the rest of your life. You make your decision, and tell Tamara...