Cassidy learns her place

Carrie happily joins you, placing her knees on either side of your thighs so the two of you can make out while Cassidy explores your huge cock with her mouth. Your hands are all over Carrie's sexy body; the feeling of her little sister's hot mouth on your cock is driving you absolutely wild.

Carrie is extremely aroused, kissing you deeply and tangling her fingers in your hair. She has to stay high on her knees, her hips pressed to your stomach to make sure Cassidy has enough room to work.

Cassidy seems shocked by the brazenly sexual nature of the situation she's walked into, but she gets caught up in it quickly and before long she's slurping and bobbing her head up and down along your shaft, trying hard to take as much of your length as she can.

You pull a hand from Carrie's body to push down on Cassidy's head. "Come on, whore. Show me you're worth all this. I thought you knew how to handle a dick."

Carrie purrs and kisses your neck, whispering in your ear. "This is so fucking hot. I love that we're doing this. Don't let me stop you; do whatever you want to my sister." She emphasizes the last two words especially, clearly enjoying the twisted sexual dynamic. "Really. I'm into it."

Meanwhile, Cassidy struggles to take your cock into her throat. She keeps pulling back, coughing, and making lewd **** noises. You nod to Carrie. "Help her."

Carrie grins and slips off of the couch to kneel beside her sister. "Okay, sis. I know it's a lot but you need to just relax and let it happen. Relax." She grabs Cassidy's head and pushes her down until the younger girl tenses and fights it, arms flailing and pressing against your knees but she doesn't let up. "Relax," she says calmly, "you can do it."

She lets her up for a breath and then forces her down again. Where Cassidy's ruby lips have been, the skin of your cock has a bright pink shade to it. A nice pigmented ring can be seen at the deepest point she's been able to take. It's barely over half. Pathetic.

Another beak for Cassidy. You hold up your hand to stop Carrie. "Look at this, Cass," you point to the lipstick ring on your dick. "This is all you've been able to take. Do you even want that room?"

She nods. Her mascara is running slightly around her watering eyes. "Yes, I do! Please, let me keep trying. I can do better."

"See that you do!" you snap, and wave to Carrie, who pushes her sister back down onto your erection.

Your girlfriend flashes you a smile as she forces her sister to gag and ****. "You're doing great, sweetie. Remember to relax."

She does start to make some progress. If you give her more time she may actually figure it out.