“Damn it, Sis,” I yelled as my nineteen-year-old sister walked into the bathroom without knocking. It was a Jack and Jill bathroom with a door leading to her bedroom and one opening into mine.  I had covered my privates with a towel.

”Fuck, Terry, ” she laughed, ”I used to help Mom change your diaper. Get over yourself.”

The bathroom was small, just a toilet, a small shower, and a vanity. She pushed her panties and shorts to the floor and sat on the toilet. I heard the tinkle of her piss splashing in the bowl. She sat no more than two feet from me. I tried to wrap the towel around my sixteen-year-old ass but she jerked it from my hand. 

”Sis,” I yelled, ”Stop it.”

She laughed as she held the towel on her opposite side. I stood there cupping my young penis with one hand and reaching for my towel with the other. She held it at arm's length as I tried to retrieve it. 

”Your not man enough, Bro,” she teased, ”I'll just keep it.”

”Come on, Sis,” I nearly begged, ”It's the last clean one.”

”Show me,” she demanded, ”Then ill give it back.”

”No,” I sternly refused, ”I'm not going to.” I reached for the towel again but she held it back. To my surprise, she grabbed me by the wrist and pulled my hand away from my penis.

”Nice dick, Brother, ” she teased, ”I don't know why you’re so ashamed of it.”

”I'm not,” I argued, ”It's just, well, you're my big sister.”

”So what, ” she laughed, ”You can see my pussy.”

Without thought, I glanced between her white thighs. Her pussy was bare and on display. I watched a droplet of piss fall from it and ripple the yellow water in the toilet.

”You like it, don't you, ” she teased as she sat back and spread her legs. She pried it open with two fingers on her right hand.

I couldn't look away. I mean, it was like I was hypnotized.  My sister was teasing me by playing with her pussy in front of me. I could hear Mom, clanging pans in the kitchen, and Dad on the mower. 

”I knew you liked it,” she squealed, ” You're getting hard.”

There was no denying the fact that my penis was starting to reveal its interest. She held my wrist so that I couldn't cover myself. To be honest, I didn't want to. Sis stood up from the toilet without her shorts.

”I'll let you watch me masturbate if you let me watch you, ” she offered. 

I watched her as she pushed herself up on the countertop. There was not enough room beside the basin for her to sit, so one of her asscheeks was halfway in the sink. She put her feet on the countertop and spread her legs. My view of her tight young pussy was uninhibited. My dick was at full attention now. 

Sis twirled her fingers around the nub at the top of her slit. I think that's what they call a clit. I found myself stroking my cock. My eyes were on her pussy and hers on my cock. Soon I could see the wetness of her sex, running onto her little pink asshole. She pushed a finger inside herself. 

My eyes were wide and my breath was becoming fast. I could feel my heart beating wildly. I was standing right in front of my sister when it happened. My dick spat long, white jets of cum all over her blouse and pussy. She jerked her fingers from her sex in fear of getting some inside. 

Sis pushed me back with her foot and jumped off the vanity. ”You little pervert,” she scolded, ”You weren't supposed to get that all over me.” With that, she stormed from the bathroom, slamming her bedroom door.