Slam your head into the ceiling

You sit up in bed, which would normally be fine. But not today, as you're in the top bunk and so your forehead slams into angled roof of the attic-turned-bedroom you share with your sisters. You lie back down, and more carefully wriggle over to the ladder, then climb down it.

You were born second of you three triplets, but were the outlier in most other respects. Your sisters were identical, and looked like near-clones of your mother, while you were like an offcut, and took more after the father who had abandoned you. They had both already dressed, in matching knee-length black pleated skirts and puffy, frilly white blouses, which almost blended into their flawless, almost luminous porcelain skin, which effortlessly offset against their straight, sable hair. You quickly pull yourself into a mid-calf length green summer dress, which you liked for its contrast with your frizzy red hair.

On a half-remembered whim, you ask your sisters a question: "Would you rather be forced to honestly answer all my questions, or be unable to urinate except in public?"

They both quickly answered "Answer you honestly, of course. We don't want to be forced to do the second one, even though it is fun."

That gave them an eyebrow raise, and then asked "what sexual fantasies do you have?" We were normally very honest with each other, so they weren't too surprised.

Anne answered first: "I want to be fucked in public, with as many people watching and using me as a toilet as possible, and then have to walk home in ruined clothes." Anna, your other sister, waited a few seconds then said: "I want to fuck Anne in public, and be covered in her cum."

Wow, you think, my sisters are really freaky. And the dream was real. I wonder if I can change reality more directly.

"Hey, would you rather have your breasts be larger, or your arse be larger?" I ask curious not for their answer but for their reactions. Anne and Anna both respond "tits." and are suddenly surprised when their chests expand and their blouses go from puffy to smooth. "Wow."

"What just happened, Allie?" Anna asks, shocked. "Are you some kind of witch?"

"I don't know. I just ask would-you-rather questions, and the world changes because of them," you respond, equally shocked that it worked.

"Wow. If I had that power, I'd probably make myself really rich, then really sexy, then go out and get fucked." Anne's voice was almost wet with her desire for that outcome.

"That's all interesting. But Anna, would you rather I grew a cock now and was still treated as a woman, or was born with a cock but treated as a woman?" You ask, hoping the question would be accepted as a real choice.

"Ooh, I see what you're doing there. I don't think we'd be sleeping in the same room if the latter, so I want you to grow it now." As she spoke, you fall to your knees, a near-orgamsic pleasure racking your body as, just above your clit, a fully formed -though slightly below average size- cock and balls errupts from your skin, causing a slight bulge in your dress. "I see that that has worked!"

"Wow, I wasn't expecting that," you whisper while pulling your skirt up to reveal your new dick nestled in your wirey copper pubes. You look over at your sisters and it begins to harden. "And it seems to like you just as much as I did."