My step-sister, Caitlin, is a couple years than I am.  But she was the hottest girl I'd ever seen.  She had huge tits.  She was tanned fine, and I could only imagine how her pussy was.  Everytime I had to stay at my father's house, I jacked off to her at night, in the shower, whenever. 

One noght she caught me jacking off.  I was doing it, and she opened the door to ask me something, and she saw me naked on the bed, jacking saying, "Oh Caitlin"  When she opened the door and heard me I said "Oh fuck!" and she said "Oh my god!"  After that she didn't say anything else she just left.  I was afraid she was gonna tell my dad, but she didn't and I didn't know why, until the next day. 

The next afternoon my dad and step mother went to vegas in the morning for a week long trip, they were never around much anyway.  But I decided to go for a swim.  

Five minutes after I jumped in, so did she in the tightest bikini I'd ever seen.  I got a boner at that instant.  As we swam she kept playing pool tag with me.  At one point she got under me and pulled my trunks off.  Underwater I screamed "Whoa!"  She was laughing.  We came up to the surface, and I said "What are doing?"  And as she took off her top she said, "You know what"  Then she grabbed me as if she was hugging me and swam me over to the steps.  Once we got there she said, "Rip off the bottom!"  So I grabbed both ends and pulled and ripped.  Her bottom came off, and she and I were naked.  Then she said, "Carry me to my room"

Once we got to the room, I layed her down on the bed, and then she said sit in that stool.  So as I was sitting she opened her dresser droor and pulled out a condom.  She came to me and got on her knees.  Then she put my dick in her mouth.  She sucked and blew hard.  I was in heaven.  Then she put the condom on me.  I picked her up and threw her on the bed and got on top of her.  She said, "Come on fuck me, and do it hard!"  I felt on her pussy and put my figer in it, she kept going, "Oh yeah", then I switched the finger to the dick.  I constantly slid my cock in and out of her pussy, and as I did so she moaned and groaned, "Come on, fuck me, fuck me harder!"  So I did, I fucked her as hard as I could.  She kept screaming.  The we flipped sides.  She rode me like a wild bucking bronco.  I was in more heaven.  She kept screaming and moaning.  Then I grabbed her and pushed her up aginst the headboard and fucked her harder than ever.  "Yes, yes, don't ever stop fucking me!", she yelled.  The I cummed all inside her.  She orgasmed, and so did I.  I pulled out the cock and layed on the bed drenched in sweat.  As she was sweaty too, she came over and said, "Let's go take a shower!"  And then she whispered in my ear, "Next time I'll bring a friend."