Filled my slutty stepsister's pussy with semen

My family and I were watching a movie on a quiet Saturday afternoon. I was bored, so I started touching my stepsister and seeing what she said. That made her horny, and she started teasing me with her tiny perky tits. She pulled out my cock and began jerking me off while I pulled her panties and got under the blanket with her.
I started slowly fucking her until mom and dad went to the kitchen. That's when I began to fuck her harder, filling her pussy with semen. She got scared and started to talk louder, and that's when our parents came out from the kitchen and caught us. Whoops!