Zack adapts his plan and goes for her panties

Zack tried to reach for Mackenzie's shirt again, but found he couldn't reach it with the redhead leaning so far forward. But what Zack did notice was, with her low-rise jeans, Mackenzie was letting quite a bit of her underwear show above her pants.

Getting an idea, Zack pulled the staple out of his exam and bent it into a hook shape. He snapped off a length of thread from his pile and tied it around the metal sliver several times over. Then, under the guise of picking up a dropped pencil, Zack leaned down under his desk. He reached forward and very gently hooked the staple through Mackenzie's panties. He managed to snake it right under the waistband, so it wouldn't just rip through the fabric if yanked too hard. He ran the string over his desk and sat back upright.

He gave a few light test tugs, and every thing seemed to be holding together. Then, Zack gave the line a somewhat powerful yank.

The effect was immediate. Mackenzie stiffened at the sudden pulling sensation from her underwear. Zack pulled again, even harder. Mackenzie sat back, wondering why she was suddenly getting a wedgie from her panties. She blindly reached behind her, trying to swat away the hand she was sure she'd find. But when Zack let the line go slack, Mackenzie had no way of knowing it was him. At least, not without looking behind her.

While she was sitting upright, Zack took advantage and grabbed the loose thread again. He wasted no time in resuming his work unravelling Mackenzie's meager shirt. But as he pulled on the thread, he would also yank Mackenzie's panties higher and higher. The redhead winced each time as her underwear dug uncomfortably into her crotch.

Mackenzie knew the asshole behind her had to be behind the wedgie somehow. But when she tried to glance behind her, the professor noticed and said "Eyes forward, please." So the redhead was stuck simply feeling behind her for his hand. But no matter how much she tried to grab it, she could never find Zack's hand.

With little else in the way of options, Mackenzie covertly unbuttoned her borrowed jeans. She slid her hand inside and began trying to extract her panties from their uncomfortable position. But each time she tugged it loose, Zack pulled it back even tighter. Eventually, the strain became too much for the cheap panties, and the seam on the bottom of them split apart.

Their waistband suddenly shot upwards on Mackenzie's body. It wound up sitting about level with her navel, with the two torn halves of the underwear dangling from the front and back of it. Mackenzie just barely managed to stifle a gasp at the sudden release of tension. But no sooner had she realized what had happened than Zack gave another powerful tug. Under the now horizontal strain, the overtaxed waistband ripped and was quickly reeled in by the lucky boy. As Zack resumed his work unravelling Mackenzie's shirt, he took a moment to appreciate a new sight. The top of Mackenzie's ass was hanging out of the undersized and low-rise jeans.