But the closer she got to Biff, the less she felt that primal need. And, unbeknownst to her, the more the color of her panties shifted from black to pink. Sarah was acquiring Tiffany's sex drive and promiscuity, and in that process, Tiffany was losing it. By the time she reached Biff, she no longer had any sort of sexual desire, but inertia pulled her, and she in turn pulled him, into a nearby closet.
As soon as the door closed behind her, Tiffany flicked on the light switch to find Biff with his jeans halfway off.
"Wait, Biff."
He paused and looked up at her, belt at his ankles, one foot in the air.
"I don't want to screw you."
"What?" Biff's foot dropped, and landed somewhat uncomfortably on his belt.
"I just need to trade underwear with you."
Sarah's wish was coming into effect. Biff could feel his cheeks heat up in embarrassment, but the magic forced the words "yeah, sure" out of his mouth as he finished removing his jeans, and offered Tiffany the boxers he had been wearing.
Of course, the small, lacy, hot-pink garment that had been handed to Biff shouldn't have been able to rise past his knees. And, of course, the sturdy black garment that Tiffany received would have easily fit over the skirt she was wearing with room to spare.
But the Tiffany that came out of that closet had traded cheerleading for weightlifting, short skirts for comfortable pants. She had gained a few inches in height, but mostly added to her width. Her bulldozer frame was formidable, and her hobby required her often to wear utilitarian undergarments, but she never betrayed her underlying femininity.
She turned to Biff, now in possession of her former height of 5'4", a height he not-coincidentally now shared with Sarah McMillan. The lace of the underwear he was wearing had filled in to solid, full-cover, pink cotton, as Sarah absorbed his height.
"You're the best, Biff," Tiffany smiled down at him. "I can't believe I forgot my boxers at home. I've got a meet right after school!"
Biff's face heated up again. There were rumors that he just hung around Tiffany because she let him in her pants, but that only happened in the very literal sense on occasion. The two had a completely platonic relationship, and Biff would never betray his girlfriend, Sarah. There are not many men in this world who would wear pink panties for a friend, and not many people for whom those men would do it, but Biff was one of those men, and Tiffany was his person.
