Girlfriend jerks me off by the sea

The day before yesterday me and my girlfriend went down to the sea for some sunbathing. It was a very warm day and there wasn't much wind, so after sweating it out for an hour we went for a swim. The water was very cool and when we got out again my swimming shorts were all cold and uncomfortable. I was feeling a little adventurous, so after looking around to make sure no one was watching, I pulled them down.
"What are you doing?" my girlfriend asked. "People will see you!"
"I'll just lie down behind you and you can cover me," I told her.
She just laughed. "You are such an exhibitionist. You get off knowing that people can see your butt!"
"Yes, I do," I smiled back at her as I lay down on the towel next to her. I had to adjust my cock under me, because it was growing a little.
We lay there on the towel for a while, and my cock grew just as hard as the rock under me, and I told her so.
"We can't do anything about that now, baby. There are people around," she told me.
Aww, I was so horny!
After a while my back started hurting from lying on the hard rock, and I sat up, making sure to hide my erection behind my crossed legs.
My girlfriend looked at me and my predicament. "We really need to do something about that."
She sat up behind me, and pressed her big tits against my back. My cock grew even harder when she reached down between my legs and gave me a little stroke.
"Not here, though." She started looking around for a place to hide. "Come on!" she told me and got up.
I grabbed the towel and wrapped it around my hips. It did absolutely nothing to hide my hardon and I followed her with a massive bulge strecthing the towel in front of me.
We found a spot in the shadow of a big rock where we would be mostly hidden from view of the other sunbathers.
"Sit down here," she told me and patted a smooth rock. I did, and she pulled open the towel. By now, I could tell she was almost as horny as I was.
"Mmm, you are really horny today!" she told me as she grabbed my boner and started stroking it.
"Mmm-hmm," I replied as I closed my eyes and just enjoyed the sensation of her soft hand sliding up and down my shaft.
She leaned in and started kissing me, her tongue flicking against mine. I didn't care if anyone was watching. I just went with it.
"I want to see you stroke yourself," she told me and pushed my hand down on my cock. I started stroking it for her. "My my, you really ARE big today!"
"You make me this big and horny," I replied and cupped a hand around one of her tits. The nipple was all stiff against my palm.
"Mmm, I want to see you cum," she told me as she looked around, making sure no one was watching us, and I wasn't hard to convince. A few more strokes and I felt the orgasm building in my balls and I told her so.
"Just cum baby."
And I did. Damn, what a lot of cum there was! I just kept pumping spurt after spurt all over my stomach and I saw it running down over my shaved balls and down between my legs and buttocks where it dripped onto the rock. I just came and came and came until there was nothing left and I drew a big sigh of pleasure.
"Mmmm, baby, you came so much!" She was obviously very impressed with the result and rubbed cum all over my stomach.
"Now go and clean up, sweetie. We need to go home."
Wow, that was the best outdoor sex we've had this weekend. Stay tuned for our next adventure!