You projected your power onto your sister, wanting to replace her pussy with something of the male variety. However, you wanted to give her realistic genitals for now, for some reason the thought of her having a regular sized cock seemed hotter to you than some enormous baseball-bat-dick.
In a flash, you sister was now bottomless, sitting on the couch with her legs spread wide. She was idly stroking a respectable 7 inch girthy circumsized penis with her right hand, while flipping through the channels on the tv with the remote in her left. Her new male genitals were clean shaven, except for the pubes above her cock which were neatly trimmed. You smiled at the sight of your sister brazenly pleasuring herself right there in the living room, fapping such a manly tool that was wedged tightly between her thick gorgeous thighs.
"Hey Jen, what's up?" you asked her.
She looked up at you in the doorway, not even minding you were watching her masturbate.
"Oh hey Ben, nothin much," she responded. "Just watchin tv and jacking off."
"Nice. Mind if I join you?"
"Nah, not at all."
You crossed the room and sat to Jenny's left, giving you a close up view of her fat schlong as she stroked her hand up and down its length.
You were curious about making a change to yourself, like you did to Jenny. Focusing on your own genitals, you felt them suck into your body. It was the strangest sensation as your cock and balls quickly formed into a fully-grown vagina inside your pajama bottoms. You made your new pussy a little bigger than a normal one and a little on the meaty side. Fat puffy lips enclosed your dark dripping folds, capped at the crest of your new labia with a pinky-sized clit. You felt a heat between your legs and a dampness as you grew wet while watching your older sister play with her meat.
Growing increasingly horny, you interrupted Jenny by reaching your right hand over and gripping her dick.
"Here, lemme help," you grunted, desperately wanting to feel her cock due to the horniness from your vagina.
"Oh, thanks Ben," she replied, moaning softly as you worked her. After a moment, she then said, "Well, if you're gonna stroke me, than I should at least finger your pussy."
With that, she unceremoniously shoved her left hand down the waistband of your pajamas and dove three fingers into your drenched coochie.
You gasped at the sudden foreign sensation, feeling insertion for the first time.
"What's up with you, you're so tense," Jenny noted. "It's like you've never fingered yourself before, haha."
"Uhh! N-nah," you stammered. "It just... it's been a while."
"What, you didn't use your dildo last night?" she asked, confused.
Not even giving this odd question any thought, you just played along. "No, uh, I was --mmh!-- tired."
"Huh. Well... it's your vagina I guess," Jenny concluded.
Your sister was now diving four fingers knuckle deep in your honeypot, and you responded by tightly gripping her dick and roughly fapping it in your hand.
"Ben, I'm about to fucking cum," your hot older sister told you. You yourself felt a female orgasm approaching.
Your sister cried out as her swollen seven-incher erupted, shooting several ropes of cum onto the living room carpet. Simultaneously, the walls of your vagina clenched around her fingers and your clit squirted discharge into your pajama bottoms, making you roll your eyes back and gasp like a whore.
Due to the "normalness" of you and Jenny's genitals, the orgasms didn't last very long. Your sister only fired about seven or so rounds of semen from her fat shaven balls before her dick was expended. Your female climax similarly only lasted about ten seconds or so. However, the newness of it to you made it incredible anyway.
You and Jenny panted as you basked in afterglow. She pulled her soaked fingers out of your snatch and you released her softening dick from your cum-covered hand.
"I love a good morning nut," your sister stated. "How about you?"
"*huff* *huff* Yeah," you replied.
Jenny resumed flipping through the channels. Keeping her attention to the tv, she then suggested, "Well, I'll be ready to go again in a few minutes, if you wanted me to fuck your pussy."
You were surprised with how openly she just said that. You watched as she idly massaged her flaccid penis with her free hand, squishing it against her balls and playing with its shrunken length in her fingers.
Obviously since you now had a vagina, you had no refractory period and were of course physically able to go again.
But did you want to settle on sex, or start changing Jenny more significantly?