A Free Use Slut?

Mark had left her 20 minutes ago, but Bessi was still laying in bed in the aftermath of what had just happened. Mark had just been there to fuck her, because she got gigantic tits, and maybe also because she made him appear at her room's door. But then this wasn't how a girl should be treated. Girls should be treated with respect, decency... all that she had been told. So as some form of payback she kept his dick fully erect, and who knows, maybe that would come in handy in the near future. But as she kept running through those memories, how he treated her like a sex doll, humiliated her repeatedly by calling her a slut, she realized she should feel angry about this. But instead she felt aroused. Intrigued even. The idea of boys just using her, fucking her whenever. Like she's sitting in school, and then Mark just appears from behind, bends her over without warning, and slams his dick into her pussy from behind. Repeatedly hammering her against her desk.
"Fuck... I am horny again." she laughed.

She got back up into a sitting position and stared at her absurdly slutty reflection. She was happy she did not accidentally turn her brain into a slut brain, even though it did sound good on the first though. But then she was also too scared that she would no longer be able to turn back. Either because she no longer could, or no longer wanted to. She knew she should turn her body back to normal, get those ridiculously huge tits down a few sizes, but just staring at herself and thinking about what this look would do to boys kept her pussy boiling. And not to mention what would happen if any dick got close to it. After a bit of inner debate about the risks and her newfound sexual fetish, she decided for a compromise.
"Among boys around my age I am known as a free-use slut that you can just fuck whenever without asking." she said and snapped her fingers.

Her heart was trembling, as this was borderline insane, and certainly dangerous. But then she could just snap things back if it got out of hand. Nothing happened though. No one appeared, she didn't have a spontaneous urge to fuck someone, nor was she chained against a wall in some pervert's basement, which had been one of her potential disaster scenarios. She scrolled through her phone, but aside from the fact that she had those gigantic tits in most of her pictures, there was nothing in particular that looked off. For a moment she figured it might have been too subtle to actually work, but before she'd try anything more drastic, she decided to check with her brother and how he would now react to it. So she got herself up, put on just her panties, as nothing was capable of hiding those tits anyways, and with a bit of a shiver running down her spine left her room as slutty as she was.

"Hey bro." she greeted John.
"Hey sis." he greeted back. He had one hand on his gargantua cock, gently working it, and with the other one he was playing some game.
"Just wanted to check how you are doing." she tried some idle chat. John eyed her, reminding her that from his perspective nothing out of the ordinary had happened, and that gigantic dong he sported was completely normal. He did however pause his game, get up, walked behind her, and with a gasp she felt his dick slide between her legs and his hands sinking into her ample tit-flesh. For a moment Bessi was confused, also because her pussy was suddenly perfectly ready. And when she looked down she saw John's dick sandwiched between her rack. John had his hands deep in her flesh and squeezed her tits around his shaft, gently tit-fucking himself using her body.
"How was Mark?" he wondered. Bessi had troubles answering, as her massively increased sensitivity of her boobs still easily fried her brain.
"G-oo-d..." she moaned.
"The only other guy in town who's dick doesn't go down either." John laughed "Wonder if it has the same cause. Like we both ate some contaminated burger or something." Bessi had troubles following, because at the same time John was just speaking his mind, he also went wild on her tits.
"May... be..." she panted. Also John was getting close, she could tell from his moans right behind her. Eventually he stopped briefly, moaned even louder, then squeezed her tits tightly around the tip of his dick, followed by a massive gush of sperm erupting from his cock and hitting her partially in the face, but mostly on her front.

"Best sis ever." John gasped and slowly slid his dick out of her cleavage. "Wish I could put that thing into your pussy, but I don't want to hurt you." Bessi was too confused and still too aroused to answer. She didn't cum, she was still riding the edge, and her body was still on fire.
"You ok?" John wondered.
"Y-es..." Bessi felt her body shivering. Sperm was dripping from her down onto his carpet. She knew it would vanish soon, but the fact that he didn't even ask, nor hint... He just grabbed her and used her like a sex toy. A part of her was disgusted, but then she also was very aroused by what had just happened. And she could only imagine what this would cause her to experience in the near future.