Helping Out Girlfriend's Sister

"Uh huh," replied Jess, he eyes closed. "I am thinking about her. About all the times she bragged about this cock. Fuck me, it's good."

"Please, we have to stop."

As in response, she started bouncing. Her wetness. My pre cum. The oil. All of it mixed in a wonderful slippery mess. My cock was ready to explode.

"Not until you give me your cum," she said, in between breaths. "I've worked hard for it. I deserve it."

"Please. Stop."

"Cum for me."

"I can't..."

"Now."

As if my some other worldly force, she hit the right spot on her last bounce and I erupted. A morning's and afternoon's worth of teasing spurted out of my cock.  Deep inside her pussy. I don't know if she had realised, or enjoyed the power, but she carried on bouncing. My spent cock was still hard from the day's events but was now getting extra sensitive with each stroke.

"Jess, I've cum. You can stop. Please."

She wickedly look down at me, put a hand on my chest. My cock was now so sensitive, each movement was torture. She bounced a few more times for good measure. The oil and my cum mixing into one big mess against our groins. It seeped out of her pussy and onto the table with each bounce. And then she stopped.

"Good boy," she panted.

I wiped away a tear as she ground her clit into my groin for good measure before she got off me. She then picked up my towel and threw it to me. I let it hit my chest.

"Come on," she said. "Take a break and clean up. We're not finished yet."

I glanced up at her, as she was bending over and looking in her bag. I saw my cum dripping down her leg.

"What? You want more?"

She turned round and looked at my slowly deflating, fully spent, cock.

"Oh babe, I don't think you've got another load in you for a while," she smiled. "But you got to come. So now it's my turn."

And with that she opened her bag to show me what was inside. I was in for a long afternoon.