Sheri was sitting on the couch, watching Cops with a vacant stare while munching on some Chee-tos, when it began. It started with a sensation of heat across her chest, followed by a neck cramp. She rolled her shoulders, trying to get suddenly-tight muscles to relax. When that didn't work, she got up and absentmindedly rubbed her shoulders as she walked to the air conditioner. She was feeling hotter now. "Piece of junk," she muttered, and gave the air conditioner a good kick. It, of course, just sat there.
She headed back for the couch and her ice water, hoping that would cool her off. Before she got there, though, the heat went away, leaving only a dull, throbbing ache. Sheri slipped a hand under her cotton t-shirt and rubbed her breasts through her bra. She felt one areola peeking over the top of her bra. Either it was that time of the month or the salesman had sold her the wrong-sized bra.
"Surely it's not my breasts growing for some unexplained reason!" she said quite perkily.
Thirty minutes later, when the heat came back again, she discovered that it was not that time, and that her discomfort was not due to a salesman's errant grab in the bargain bra bin. This time the heat and tension came and went quickly, but the throbbing pain was more intense than before. Worse, now her bra was pinching.
In the bathroom, she found that her once-small breasts were now noticeably bigger. She pulled off her shirt and stared at the flesh welling up over her cups. Off with the bra, and sure enough, what once were mere swellings on her chest were now easily cuppable.
"Oh, no!" she said. "What's happening?" Sheri pulled her t-shirt back on, leaving the bra off for now, and headed for her bedroom. "I hope I didn't get infected with Dr. Mam's nanites!" Dr. Mam, one of the scientists at Improbable Science Incorporated, was working on nanites to speed cell growth in order to help the hungry. Or were they to help the injured? She never could remember.
"Or maybe Dr. Cupsize's little-understood virtual reality machine is behind this!" She'd tried out the suit for Cupsize just that afternoon. Secretaries at ISI were expected to help out the scientists however possible, after all.
Then again, Dr. Bigguns had been experimenting with those odd balloons. And Dr. Juggs worked on a body-recombinator/TV-remote project on the side. Plus Dr. Suggestivename had been monkeying around with pills that unbound the hydrogen and oxygen in water, causing things to swell up surprisingly big.
"Surely that cloud of strange gas I drove through on the way home didn't cause this," she thought aloud as she took off a necklace made from a glowing chunk of meteorite that she always wore and threw it in a dresser drawer, where it landed on top of a spell book called "Incantations: Your Body, Yourself" and a creepy voodoo doll that looked like her, only with gargantuan titties, which the lecherous old man in the apartment across the hall had given her.
What could she do? She couldn't call her bosses at work. They might kill her to keep their projects secret, like they did that other secretary who grew an extra hand last month, and besides, they hated being called on the weekend. She couldn't call her doctor. Actually, she wanted to call her doctor, but had the vague feeling that that was entirely too sensible a plan for a story like this.
There was only one person to call: her boyfriend.
Jack showed up ten minutes later, still wearing his Domino's uniform and carrying a large pizza with pepperoni and extra cheese. "Hey, babe," he said, "why'd you call?"
"Yum! Pizza!" She grabbed a piece from the box and wolfed it down. "Oh, yeah," she said around a mouthfull of dough and tomato sauce. "I guess I better tell you why I called."
She swallowed the last of the pizza, then lifted her shirt. Her breasts had grown some more while she had waited for Jack. They now were the size of some not-too-large piece of fruit, maybe an orange or an onion. Though she wasn't sure if onions were fruit.
Jack stared happily. "Cool!" he said, before burying his face in her boobies and sucking on them happily.
Sheri pushed him away. "Stop that! That's not why I called you!"
"I didn't even know you were going to get implants!" Jack said. "Not that I mind," he added quickly before nuzzling her breasts again.
"I said stop that!" she said, pushing him away again and yanking down her shirt. Out of sight, out of mind and all that.
"Then why'd you call me?" Jack whined.
Sheri sighed. "They're not implants."
"They're not?" He reached out and gave her tits a quick squeeze. "Yeah, they feel real."
Sheri drew back, then looked at him angrily. "How would you know? Been feeling a lot of breasts lately?"
"Look, I'm the guy in this story. I've got an encyclopaedic knowledge of breasts, bra sizes, and implants."
"Oh. Okay."
"So if they're not implants, where'd they come from?"
Sheri sat down. Jack sat next to her. "You know all those projects at ISI I can't tell you about?"
"Yeah?"
"These," she lifted her breasts and let them fall again, "probably came from one of them. Unless that potion I added to my Slim-Fast last night actually worked...."
"What are you talking about?"
Sheri felt her chest grow hot again. "This," she said, grabbing Jack's hands and putting them on her chest. Her breasts grew hotter and hotter, then cooled and began to swell, pushing out against her shirt. They spread out as they did, until they comfortably filled Jack's hands and then some.
Jack's eyes widened. "Your boobs are growing!"
Sheri nodded. "Every once in a while they get real hot, and then they grow."
"Heat, huh?" He scratched his head. "That's probably just a lame attempt to make this seem real. Chemical reactions releasing heat, etc. etc."
"Like I give a shit. I just wanna stop this!"
Jack looked at her. "That's not right. You're supposed to like this."
"Like this?" Sheri grabbed her breasts and pushed them up. "What happens if they keep getting bigger until I can't move?"
Jack kissed her. "I'll still love you. Besides, you'll grow to love your new endowments. You'll find work as a stripper, or just lie around the house having orgasms all day. It happens in all the stories."
Sheri thought about it. "Okay!" she said.
They sat there quietly for a minute. "Uh, Sheri," Jack finally said. "I know one way we might be able to stop your growth. I mean, if you really want this to end."
"Is it going to involve sex?"
"Oh, yeah, baby!" He nodded eagerly.
Sheri thought about it. "Okay!" she said. "Let's get it on!"
They went into the bedroom and got it on. Jack was normally a pretty timid lover, but tonight he was a tiger. They hardly made it inside the room before Jack's hands were all over Sheri. Up and down, up and down, he ran his hands all over her, especially over her newly-grown mammaries. Sheri loved it, and basked in the attention. She found that her newly-grown mammaries were very very sensitive.
Her breasts must have appreciated the attention, because they shortly grew warm again, so warm that Jack noticed. "Can I...?" he asked.
"Yes, yes, oh yes," she whispered back. She put her hands up and held both her breasts and his hands. The warmth faded and the growing began. There was pain, but ecstasy overwhelmed it. Her nipples jutted out; her areolae were puffy. She felt her skin tighten over her tits as they grew, then grow soft and supple again as the growth ended. Jack was having trouble holding both breasts now, and Sheri felt new sensations racing through them, leaving jangling nerve-endings in their wake.
This must have excited Jack even more, because he nearly ripped her t-shirt in two pulling it off of her. They fell onto the bed, Sheri knocking off Jack's Domino's hat, Jack rubbing her boobs twice as fast as before.
By the time Jack and Sheri came to a shuddering climax, Sheri's mams had grown and regrown. Jack rolled off Sheri and put both hands on one of Sheri's tits. They had gotten so big Sheri had a hard time coming up with fruit to compare them to.
"Casaba melons," Jack said. "Or maybe watermelons."
"Yeah!" Sheri said. "Wait, how'd you know I was trying to think of fruit like that?"
Jack smiled. "That's my job. I'm supposed to compare your titties to fruit."
"Great!" Sheri said. "That's a load off my mind. I was having all kinds of trouble thinking of fruit my breasts reminded me of."
They sat there for a while, watching Sheri's breasts. Finally, Sheri said, "I think they've stopped."
Jack reached out and gave her right mam a tentative squeeze. A little fluid collected at the nipple, then dripped onto the bed. "Cool!" he said. "Milk! This is perfect!"
"What do you mean -- hey!" Jack had put his lips to her nipple and was sucking hungrily while squeezing her breast. "That -- ooh, that feels kinda good!" She leaned her head back and tried not to feel too much like a cow. The feeling of Jack's mouth on her nipple helped distract her.
Jack finally came up for air, a little milk still on his lips. "This is going to be really sweet."
"What do you mean?"
"See, in all these stories, when a woman's tits grow and she starts giving milk, other people who drink that milk get bigger! Women's breasts grow and men get big cocks." He reflexively put his hand on his limp little member.
"Huh. That's really weird," Sheri said.
"It's not weird," Jack said, "it's just what happens." He smirked. "And now it's gonna happen to me."
Sheri shook her head. "No, I can believe that other women could get big breasts, but I don't understand why men would get big dicks."
"I'm telling you, that's just what happens! It's in everything I've read. You milk's like some kind of sex juice."
"Yeah, but breasts are, um, whatchacallems. Secondary sexual characteristics."
Jack shrugged. "I don't get it."
"Well, your dick is a primary sexual characteristic. If my milk does stuff to people's secondary sexual characteristics--"
"Shh! I can feel it starting!" He stood up and looked down at his crotch. "Oh, yeah, I feel my dick getting warm!" He rubbed his cock, then dropped it. "C'mon, grow! Grow!"
For a second, nothing happened. Then the hair around his dick suddenly grew so thick Sheri couldn't see his cock any more. "Hey!" Jack said as all of his hair got longer and thicker. Much thicker, in fact: his chest became covered in a mat of hair, and his beard completely filled in, starting just below his eyes and reaching to his chest.
Sheri stared at him, then started giggling. "Oh, wow," she gasped between laughs, "now you look like a wolfman, Jack!"