Jeff stood, humiliated, in his boxers and socks as his body finished turning into his new form, a big-breasted fat woman.
His male parts were gone, replaced with whatever it is females have. His fat ass strained against his underwear. "Okay, don't look, I'm taking my underwear off!" He grimaced as his higher and more mature female voice.
Jane laughed. "Oh, who cares, it's not your real body! You can get naked, we're both girls now."
Jeff hated that thought, but it was going to be physically impossible to keep his underwear on, so he pulled it off. By this point the transformation was finishing.
"Wow, I'm huge!" he said, marveling at the massive breasts and belly that were now attached to him. He groped at his boobs, picking them up and letting them drop. He did the same with his new belly.
"Yeah, you're so fat!" Jane was in hysterics now. "I want to play with it!"
"Oh, come on..." Jeff groaned but allowed his sister to paw at his heavy breasts and his fat belly. "Okay, enough, enough." He picked up his belly so he could see what was or wasn't going on between his legs. He was greeted with two fat hairy legs and a bush of curly black hair where his penis was supposed to be. "Oh, gross, it's so hairy! Yuck, my legs are hairy too!"
Jane smirked. "Well, did you ever shave your legs before? Did you shave your cock? You know women have hair the same places you do, you can shave it if you want, but you don't just suddenly become hairless because you're a woman."
Jeff honestly didn't really consider it before. He knew women shaved their legs, but he didn't put it together than they would be this hairy by default.
"Okay, fine. No, I'm not going to shave my legs. How long are you going to leave me like this?"
"I told you, get me cigarettes and beer. I made you old enough that you won't get carded. When you're back I'll change you back."
Jeff picked up his breasts again. "These are so fucking heavy. How do women live with these?" He always thought of boobs being soft and airy (having never touched anyone's before). They felt like big heavy dense mashed potatoes or something attached to him.
"Well, most women aren't built like that. My boobs aren't heavy, they're just enough. You're a big fat cow."
Jeff didn't like thinking about Jane's boobs, but it made sense, his new body was really different from hers and from most women's.
He pawed at the hairy unfamiliar genitals where his penis and his scrotum used to be. Just a big pad of fat that split into two big hairy lips and connected to his asshole.
"You having fun?" Jane was still smirking and staring.
"It just feels so weird." He looked at his hands, slightly marred and wrinkled. "I'm old, huh? How old did you make me?"
"Don't worry about it. Oh, before you go..."