Justine and I had been born exactly sixteen hours apart. We weren't related by blood, but our parents had been married long enough for us to fight like brother and sister. Justine had this cocky attitude about her that caused me to clench my fists every time we were in the room together. She knew just how to get on my last nerve, and she reveled in it.
When we were kids, we would wrestle to prove which one of us was the toughest. She was still a scrappy chick, but we hadn't scuffled since high school. To be honest, I sometimes wondered what it would be like to have her long, toned legs wrapped around me like they were when we would fight.
Justine was away at college, but she was due back home in a few days for the start of her summer vacation. I hadn't wanted to go to school, so I had stayed with our parents to learn how to run the farm. Our parents insist on hard work from everyone staying in the house, and they had left it up to me to get Justine back into the swing of things. I was to show her around the farm's new additions, and introduce her to the horses she'd be taking care of.
Justine got home late Wednesday night; hours after our parents had been in bed. I was just getting out of the shower when I heard her car pull up. When she walked through the door, my jaw almost dropped. College must have been treating her very well. She still had the long, toned legs, but she had filled out some and was now sporting the nicest set of tits I'd seen in a long time. She was wearing a thin silk tank top and a miniskirt that left little to the imagination. When I went to give her a hug, like a good brother, I nearly creamed my self as her silk-sheathed tits pressed against my bare chest. As she pulled away from our embrace, she gave me a smile that told me she'd felt my hard on pushed against her. After that little encounter, we both headed off for bed. Morning come pretty early on a farm.
The next morning after breakfast, our parents sent us off to get started on the chores. I started the tractor so we could head off to the back lot, and Justine climbed up behind me, straddling me so she could fit on the seat with me. She was wearing a pair of tight little shorts, and when she pressed against me, I thought I was going to drive the tractor into the lake.
I was finally getting control of the tractor when I felt her hand on my thigh. I tried to block the images in my head as her tits bounced against my back on the rough ride of the tractor, but I lost it when she started rubbing herself against me.
"I forgot what it's like to ride on the back of a tractor," she purred in my ear, "I've definitely missed this."
I didn't know where she was going with that, so I tried to play it neutral. "How's school?" I asked her. She started to run her hand up my thigh, barely missing my throbbing cock. "A little lonely," she answered. Lord was I in trouble. Thankfully, we had just pulled up to the barn to grab the hay for the horses. I jumped off that tractor as quick as I could to put some distance between us. If I didn't, I was going to take her up there on that tractor, and that just felt wrong. We may not have the same parents, but she's still my sister.
I ran into the barn and started grabbing the hay. I figured if I worked hard enough doing that, I would forget about what Justine was doing to me. No luck. After stacking twelve bales of hay to go out, my cock was still as hard as cement. I stopped tossing the bales to wipe my face, and when I looked up, Justine was standing in the doorway of the barn.
"Need any help?" she asked, licking her full lips.
