One of the housewives, Sherry, volunteers.

"Sherry! Perfect!"

As Monica pulls away from you, one of the older participants comes quickly up to take her place. Sherry is a light brunette, probably in her 30s. She seems fit, if not exactly muscular- her tank top shows off her arms and clings tightly to her chest and stomach. What really catches your attention is her lower half- Sherry had wide hips that she almost seemed to shimmy as she sauntered up to you. As she takes her position standing in front of you, facing away, you see that she has an ass to match, a big butt that jutted towards you and strained the yoga pants she was wearing.

"John?" Monica said, snapping you out of your staring, "if you're done admiring the view, Sherry's waiting to demonstrate."

This caused the class to erupt in another fit of giggles, and you were glad that most of them couldn't see the bulge in your shorts past Sherry. To her credit, Sherry was giggling too, looking over her shoulder with a grin and a raised eyebrow. "Come on, hun," she said, and you blushed as her eyes darted down for a moment, "I won't bite unless you ask."

You stammer out an apology, which Sherry seems to wave off, as you stepped forward, trying to grab around her arms while both keeping your hands off of her chest, and keeping some distance between your erection and her body. Sherry wasn't having it though; grabbing your arms, she pulls you forward, and your front collides with her back. Once again, your shorts and her tights provide the bare minimum of padding, but Sherry's different from Monica. Monica's butt was tighter, firmer, but also much smaller. Sherry was big and soft, and you could feel your manhood being enveloped perfectly between a pair of pillowy cheeks.

"Oh!" Sherry burst into giggles, and pulled you by your arms even tighter against her back. "Um, Monica? When being attacked from behind, is it strange to feel the assailant, uh, 'poking' you?"

Monica was grinning wide, staring straight at your rapidly reddening face. "Not at all! There is a chance that you could feel an attacker's erection, so it's important not to let that catch you off guard." Monica winks at you. "Thank you, John, for being such a good practice example!" The other students voice their agreement amidst whistles and shouts for a better view.

"I think I can definitely appreciate it..." Sherry says. She sways her hips back and forth slowly, the grinding caress on your penis making your knees wobble. "Now, how did this go?"

It feels like an eternity as Monica talks Sherry through the routine. First she weakly stomps down on your foot, leaning back into you as she exaggeratedly raises one foot before bringing it down. You get whipped in the face by her hair as she mimes a headbutt back at your face, and your breath hitches as she slides down slightly, ducking out of your grip as she bats your arms up away from her. Finally, she steps away to kick- "Aim the kick to the knee, stomach or groin," Monica explains as Sherry demonstrates- and sure enough she aims for your groin, her bare foot lightly batting at your bulge, now visible for the entire class as part of the demonstration.

"Very good, both of you!" Monica claps, and the rest of the class joins in. Sherry seems happy, but you feel lucky to be on your feet! As it is, you feel about ready to burst from all the sliding against you your demonstration partner did. You nearly fall over when Monica asks if anyone needs another demonstration.

"Hey, uh," and you cough, trying to knock the wavering out of your voice, "maybe we could break for a minute?" A laugh passes through the ladies, amidst a few cries of "we just started!" and "feeling tired already?" Monica seems to think it over- you're hoping she decides to give you a minute or two to get soft, but you realize she could just as easily have you go through all of that again, or even move on to something worse, and you don't think you can take that without making a mess...