Sharon's plan

Sharon knew Kristina was very horny and very confused. Kristina was putty in her hands. Sharon could feel her co-worker's heart racing and saw her breathing through her mouth. She was almost panting. Sharon winked at Heather who took a few more photos.
Kristina had no idea what was going on. She had never become aroused before in the company of women, but here she was as horny as she had ever been. Not only was she extremely aroused, but she kept making a fool of herself by giving herself wedgies. She racked her brain to figure out why she kept doing that to herself, but could come up with no logical explanation.
Sharon kept scratching Kristina's ass. "How's that, Kristina?"
Kristina yanked on her panties again. This time she happened to pull Sharon's finger into rectum. "Oh, Jesus, I'm sorry, Sharon," said a deeply blushing Kristina as she stood up.
"That's OK," said Sharon. "I'll just go wash my hands." Sharon smacked Kristina on the ass as she headed for the restroom.
"Kristina," said Jennifer. She paused as Kristina yanked her panties up again and winced. "Why do you keep giving yourself wedgies? Is this some sort of weird fetish for you?"
"I don't know!" said a flustered Kristina. "I can't help myself." She was beet red.
"Well, why don't you take your panties off?" said Heather.
"I guess I could. I'll go when Sharon comes out of the bathroom."
"No, dear, you're among friends. Just do it right here. You trust us. You have nothing to be ashamed of," said Heather.
Kristina thought for a moment. She did not want to alienate her friends. "Well, OK." She took off her shoes and then her jeans. She handed them to Jennifer.
"Thank you, Kristina," said Jennifer.
Kristina's panties were already half way up her back when she yanked on them again. This time they ripped over her thighs. She basicly flossed her anus as they came free. "Oh, god!" She said. "This is so embarrassing!"
"Smile!" said Heather as she snapped a photo of Kristina standing naked below the waist holding a pair of damp and torn panties. The look on Kristina's face was priceless. A look of shock, embarrassment, and a hint of arousal.