Carrie is licking Erica through her panties.

Carrie's initial lick was responsible for Erica's initial knee jerk reaction. "Oh my God, Carrie! What are you doing?" she demanded.

"Mmm," Carrie commented as she moved her head in for another lick.

"Unh... Carrie," Erica moaned, her resolve weakening. "Don't."

If the gusset of Erica's panties didn't have a wet spot before, Carrie's ministrations and copious amounts of saliva had definitely caused one to appear. She continued licking, though, enjoying watching Erica squirm. "Yep," Carrie commented. "I see a wet spot. Guess the panties are soiled after all."

"No they're n-Unh..." Erica tried to interject before being distracted by another lick from Carrie.

"Good girls don't wear soiled panties, Erica," Lisa said. "Looks like they're going to have to come off."

"No!" Erica said between licks. Carrie rendered her protests mute by diving in and sucking on Erica's clit through her panties, hard. This was enough to render Erica speechless as she was struck by an orgasm that distracted her more than any of Carrie's previous efforts. As she tried to react, her tormentors made their next move.