Refuse to help your sister.

You shake your head in refusal.

"Really, Doug, I expected much better from you," your mom says, her disappointment clearly evident. "You leave me ****." She grabs you forcefully by the arm and pulls out the chair at your desk.

"What are you doing?" you ask nervously as she pushes you down to your knees beside her and leans you over her lap.

"Something I haven't had to do for a long time."

She pulls your pants and underwear down to your knees and holds you down, your bare butt now exposed to the air and your cock dangling down toward the ground. She raises her hand up high and then brings it down to your butt cheek with a large whack. You jump at the sudden pain, but you mother holds you down in her lap. She rests her hand on your butt for a moment, before raising it again for another painful slap. You mother continues the spanking in earnest now, occasionally switching between cheeks, pausing between each strike, squeezing slightly before striking again. You try hard not to cry out, but are unable to stop as the pain in your ass grows, tears starting to fall from your eyes.

Disturbingly, you notice something hard pressing against your stomach -- is your mother getting aroused by this? Even worse, you notice that you have started to become a little hard yourself. How could this pain and humiliation possibly be arousing?

Finally, the spanking has stopped, though your mom's hand hasn't left your ass. "So are you ready to help your sister now?" she asks.

You silently nod your head in defeat.

"Then get to it," she orders.

With your pants still down around your knees, you crawl toward your sister. With an excited look on her face, she pulls down her skirt and panties, and points her dick toward you. Apparently she enjoyed the show, because she is already fully erect. You can't believe how large it is -- at least several inches longer than your own.

Intimidated, you turn your head to look at your mom. "Go on, then. Do I need to teach you another lesson?" Considering the tent in her skirt, you're sure she'd enjoy giving you another lesson, you think bitterly.

With a sigh, you turn back to your sister and slowly reach out your hand to her cock, squeezing it gently. It feels strange -- both incredible soft and yet so undeniably hard at the same time.

"Put it in your mouth," your mom commands. Obediently, you open your mouth and lean forward, your sister groaning in pleasure as she feels the warm, wet embrace of your mouth around her member. You start moving your head back and forth, your tongue swirling around her cock, your hand stroking the part of it not in your mouth. You figure the sooner you can get your sister off, the sooner this humiliation will end.

"Go deeper." You try to get as much of your sister's cock in your mouth as you can, but you start to gag as it nears the entrance to your throat.

"Deeper," your mom commands you again. You try to obey, but can't get your sister's thick head down any further. You feel your mom’s hand on the back of your head as she pushes you forward, forcing Sarah's cock into your throat. You panic as you start to ****, but the pressure against your head doesn't let up as you go deeper and deeper down your sister's dick. You mom pulls your head back, giving you a few seconds to catch your breath before forcing you back down. This process repeats, each time inching a little further down the shaft, until your face is pressed against your sister's crotch, your nose poking her stomach. Your mom now starts to work your head back and forth, slowly fucking your sister's dick with your throat. Your panic subsides as your get used to the experience, catching quick breaths when you can. Although you can feel Sarah's cock stretching your throat every time it enters, it doesn't feel as unpleasant as you expected. If fact, your arousal begins to grow as you start to enjoy servicing your sister.

"Yeah, suck that cock," your mom encourages you as your resistance fades and the pressure on your head lessens. Before long, she withdraws her hands altogether and you are bobbing up and down your sister's dick of your own free will. You enjoy the taste and texture of it in your mouth, and the shame of pleasuring your sister while your mom watches actually arouses you even more, your dick now fully erect below you.

"I'm cumming!" Sarah announces. Before you can pull back, your mom's hands are back on your head, holding it in place on the end of Sarah's cock. "Get ready, son. You need to drink it all." Your mouth is suddenly filled with girl spunk as Sarah unloads. You barely have time to swallow before she dumps a second load into your mouth. "That's it, Doug. Keep swallowing your sister's cum." With the quantity of each spurt decreasing, you are able to start appreciating the flavor. It's a little bitter, but still sweeter than you expected. Actually, you have to admit that it tastes pretty good. Finally, your sister finishes and her softening dick drops out of your mouth.

"Good work, honey." Oddly, instead of the shame you should be feeling, your mom's praise fills you with pride instead.