...the instructor told them to stand up straight and finish the forward fold

(this chapter originally by "ewong")

The instructor then has everyone begin to stand up, keeping their hands on their elbows as they release from the forward fold. Isabel takes this as her cue to pull her pants up, but she is met with a complication: Mindy has taken hold of her shorts! Isabel pulls her panties up so her ass isn't visible, and Mindy seizes the opportunity to pull Isabel's shorts down to her ankles!

Mindy looks around to see no one noticed, and is surprised she has gotten this far, and none of the other girls in the class, or even the instructor noticed what was happening. Perhaps it was the fact Isabel's panties were white, along with her shorts that made everyone think she was still clothed.

Isabel was a wreck! One moment, she had half her ass on display, and the next, her shorts were around her ankles. Now that the class was standing, they would surely notice if she bent over to pull them back up, and she didn't want to draw any attention to herself. So, redfaced, she stood with only her white panties covering her lower body as she waited for the next pose from the instructor. To her relief, the instructor had them do a similar pose, but only bending halfway, with their arms outstretched in front of them. It would give her the excuse to pull her shorts back up!

Mindy, however, saw this as another opportunity to strip Isabel some more. So, as everyone reached forward and began to bend forward once again, Mindy...