Kim felt a pang of guilt as she looked at Biff and Sarah, hiding in the bathroom. Sarah looked like she was pushing 200 lbs, and her clothes were so badly ripped and stretched that she couldn't really keep herself covered anymore. She was trying in vain to cover her huge boobs with her tiny blouse, and all she was doing was pushing more and more cleavage over her arms and out in front of herself.
Biff, on the other hand, was obviously uncomfortable with all the attention he had been receiving. He clearly didn't have any idea how to keep his modesty in these clothes, not that they allowed for much in the first place. His boobs were practically falling out, and the top of one of his aureoles was clearly visible. He was smiling and giggling almost constantly, and if Kim didn't know better, she would think this was one of the sluttiest and flirtiest girls she had ever met.
"I guess you're hiding in here because it's too hard to face the school, right?" Kim asked. "Well, I'm in a good mood from watching you two suffer, so I'm going to offer you a deal."
Sarah and Biff focused their attention on her intently, not sure whether they should get their hopes up or be even more afraid.
Kim continued. "The problem you two have, fundamentally, is that you are both so interested in serving your own selfish interests that you don't even care what happens to other people. So, I'm going to give you an opportunity to prove that you can consider someone else for a change."
"You can continue the rest of the day as planned. Biff, you're probably an hour away from getting groped by someone with about as much taste and decency as yourself - you'll see what sexual assault feels like on the receiving end. Sarah, in a few more fat jokes you won't be able to fit in your clothes anymore, and you'll have to figure out how to attend the rest of your classes without being naked."
"I'm willing to give one of you the chance to avoid all that. You will immediately return to normal, and you can do as you like for the rest of the day - stay at school, head home, or whatever. All you have to do is prove you can be unselfish, by bringing the other one to an orgasm first. If you come before the other one, you're stuck the way you are for the rest of they day. So, you'll have to put your own pleasure aside and help someone else for a change."
Sarah and Biff were silent for a long moment. Finally, Sarah said, "What if I don't want to get anyone off?"
Kim smiled. "No problem, you don't have to touch him, and you don't have to let him touch you. This is totally voluntary. If you'd rather continue your day the way it's going, then don't touch each other at all."
Biff and Sarah stared at Kim for a long time. Then they started glancing at each other.
"The bell rings in ten minutes," said Kim, "so you'd better decide quickly. And no, I'm not planning to go anywhere, so you'll be performing for an audience. On the other hand, I'll make sure nobody else comes in and spoils the moment."
Sarah reached over and gently touched Biff on the shoulder. He looked at her and licked his lips. In a few moments, they were kissing each other on the neck and licking each other's ears.
Sarah slipped a hand under Biff's blouse and started stroking his nipple gently. Biff moaned in his feminine voice, and started fondling Sarah's massive tits. Sarah slid her hand down Biff's flat belly, and slipped it down the front of his pants.
Biff let out a little squeal just before Sarah pulled her hand out as though she had stuck it in a fire.
"What was THAT?" she asked. Biff only smiled and giggled, feeling horribly uncomfortable and totally at a loss for words.
Sarah knelt down and slowly pulled Biff's jeggings and panties down. She gasped as she saw his tiny, hairless penis standing proudly erect.
"You still have a penis!" said Sarah.
"Umm, yeah..." said Biff, giggling.
"It's so tiny!" exclaimed Sarah.
Biff blushed madly, as he continued to smile and giggle. His giggle turned into a moan as Sarah wrapped her mouth around his tiny member. Then he squealed with discomfort. Sarah either hadn't given very many blowjobs before, or didn't have any idea how to do it with such a tiny cock. Either way, she was doing a terrible job - she was sucking so hard that it was painful.
Sarah sat back in surprise. Biff gathered his wits and used the opportunity to push Sarah back and pull down her torn jeans. The jeans shredded into bits as he pulled them off, leaving her shaved vulva visible beneath the roll of her belly and jammed between her fat, cellulite ridden thighs. Biff jammed his face into her pussy and started to lick. Sarah moaned, but the good feeling faded quite quickly. She wasn't sure what Biff was trying to do, but it felt like he was shoving his tongue up her twat and totally ignoring her clitoris. Clearly he had no idea what he was doing.
This moment of clarity gave Sarah an idea. She wasn't used to pleasuring men; usually she made them do whatever she wanted, figuring that it wasn't hard for them to get off anyway. She knew even less about pleasuring other women, and wasn't at all sure to do with this almost-woman with a baby-sized cock. But she realized that Biff didn't really know anything besides how to get himself off, and that was all she needed him to do.
At least Biff was drooling into her pussy a lot, giving it some lubrication. Sarah put on her best fake moan, and said "Oh God, if I had a dick inside me right now I'd come right away!"
Biff took the bait almost immediately. He pushed Sarah back so she was lying on the cold tile floor, and slid his body up on top of hers. His feminine body was shorter than hers, and he stopped to suck on one of her fat nipples on his way past. A jolt of pleasure shot through her, and she gasped. Then he tried to stick his tiny cock into her pussy. Between his apparent lack of knowledge about female reproductive anatomy, the rolls of fat surrounding her cunt, and the miniscule size of his dick, he was having a hard time getting engaged. He was accidentally rubbing his penis all around Sarah's clit, which actually felt kind of good. Worried that she might lose, Sarah reached down and tried to guide his tiny cock between her fat lips. After what seemed like an eternity of awkward struggling, she finally managed to help him find his way in.
Kim was watching in open fascination and amusement. This was terrible sex. She wanted to laugh out loud, but was worried that they might give up if she did.
Biff felt his cock slide into Sarah's vagina - as deep as his tiny cock could go, at least, which really wasn't very deep at all. He started thrusting as much as he could, which wasn't much, again thanks to his tiny cock. He thought it was doing the trick, though, as Sarah moaned and squirmed beneath him. His boobs were bouncing uncomfortably on his chest, Sarah's fat body wasn't what he usually found attractive, but her soft stomach and enormous tits held a certain appeal. Before he realized what was happening, Biff felt his cock spasm as he blew his load.
"Oh God!" he squealed in his girlish voice, and then had the strange sensation of lying on a deflating balloon as Sarah's body suddenly started shrinking back to its normal size.
"Oh shit," he said, then smiled and giggled helplessly as he felt a sinking sensation in his stomach.
