One day our grandma wanted to take us to see the first pirates of the Caribbean. It had just came out after the movie. Our grandma had to make a stop before we got some food. Well we got there me and my sister stayed in the van while GM went in. She came back and told us there was a 45 minute wait we said ok we will just stay in here. After she went back I asked my sister to flash me. She made sure nobody could see since we was right in front of the shopping center then showed me her tits. I climbed out of the front into the seat next to her and pulled my hard dick out of my basketball shorts. My sister immediately leaned across and sucked my dick until I came in her mouth. She had a skirt on so I reached out and took her panties off fingered her a mini until I got hard again. We didn't have a condom but she got up set in my lap balls deep and she just set there a minute with me in her. Then she started really bouncing up and down. I told her I was about to cum and my little sister said I'm not stopping. I went in as deep as I could and blew my load as deep In her tight young pussy as I could. Then not long after our GM came out to a van I know smelled like sex and my sister had my cum running out of her young pussy.