To Not Cum

"S-stop," it comes out of my mouth as a whisper causing my sadistic step-sister to giggle.

She speeds up her strokes and brings her lips to my ear, "Aww, don't you want to cum for me too." She grips tightly on my cock, "You already did for mom and Kara didn't you?" She swiftly brings her hands through the waistband of my grey sweatpants and grips my cock.

I gasp feeling her delicate hand wrap around my throbbing member.

"What if I want you to cum for me?" she asks in a pouty tone, "Do you not like me as much mommy or sis?"

She stroked faster and my whole body shuddered.

"Please," I said, "Don't"

This made her giggle and go faster. I could feel the edge quickly approaching and right as I was going to burst I heard a loud knock on the passenger door window.

Haley stopped stroking, but didn't let up on her grip.

I looked out the window and saw the school principle.

She was tan and blonde. She wore a blue suit with a tight skirt and enough buttons undone to show off her breasts. Her face was stern and demanding.

"Young lady," She said, "Just what do you think you're doing?"

Haley sighed then said through the door, "I was just having a little fun with my brother Ms. Domina."

"Well," the principal said, "You will be late for first period if you wait to much longer so you should be on your way."

Haley pouted and mouthed 'You got lucky' to me giving my cock a parting squeeze before saying, "Yes, ma'am." Haley got out of the car and left me alone with the stunning principle.

She stepped back from the door and motioned for me to exit. I got out and nodded at her before I made to get to my first class of the day only to hear her say, "Not so fast Mr. Smith."

I turned around to look at her standing there with a clipboard I hadn't seen her produce. "You and I need to speak, privately." She said the word privately like it was a dirty secret and I had a feeling the seductive tone of voice was intentional. She motioned me to follow her with her finger and I awkwardly followed behind her with a raging erection.