This happened on Sunday. I am 26 years old. I had been out at my buddy's bucks night all night Saturday, and my wife had been out at the hens night separately. She told me she would be staying around there the next day to recover and then go shopping. I got home at 4am and hit the sack after a hard night of drinking and watching strippers. I woke up the next morning at 10am to find myself alone in our house and horny. It was a hot morning so I opened all our doors and windows to let some air flow though the house. I sat on the couch and turned on MTV. I was really horny thinking about the strippers as well as generally being horny when hungover. I decided to get totally naked and have a nice jerk off. Our house is down at the end of a long driveway, so even with all the windows and doors open, no-one could see in unless they drove up, and I would see and hear them if they did.
Now I am a semi-pro sportsman and in very good shape. I am also 6ft 7in, and have a large cock (9in long x 6.5in around) big balls, and am totally shaven all over, the way my wife likes it. So I was totally naked sitting on my couch watching tv with my legs spread and jacking my big cock that I had lubed up. I kept my eye on the driveway to make sure no cars were pulling up.
After about 5 mins of good jacking off I must have closed my eyes and forgotten about checking outside. I was deep in a fantasy when I heard the screen door on the side of the house shut and a female voice say 'oh my god!'. My heart jumped as I opened my eyes and saw my wife's older sister Carrie standing there staring at me jacking off. Carrie is 29, single and lives alone. She is a little chubby but quite cute and has big tits, but I know she hasn't had many boyfriends over the past few years. We had always got along well in the 8 years that I had known her, but I had never really fantasised over her.
Anyway, we were both in shock and I scrambled to cover my big cock with a cushion. 'Shit, I'm so sorry I totally forgot you were coming round' I said. My wife had told me the day before that her sister was going to come round today to pick up some shoes. She said 'I'm really sorry, this is so embarrassing, I'll just go'. She was bright red and looked really embarrassed. I said 'you might as well grab the shoes, they're in the hallway'. She said 'ok' without looking at me and went to get them. She was in the hallway for about 2 minutes, probably taking in what she had just seen, and I quicky tried to put my underwear back on. She called out 'is Erin home' (my wife) and I called out that she was out shopping for the day.
Carrie finally came back into the living room and said to my shock 'Look, I'd love to watch if you want and its ok?' I didn't know what to say but was so turned on, as she must have been. I said 'Only if Erin never finds out and we never speak of this again'. She agreed and I told her that I would never cheat on my wife. Carrie, still bright red, slowly sat in a loungechair opposite me and looked at me with the horniest look I've ever seen. I was rock hard and my big cock was bursting to get out of my tight jocks. Carrie had her mouth open and whispered 'show me it' and then said 'this is so wrong.'
I pulled my jocks off and showed my sister in law my fat 9in cock. She gasped and said 'oh my god, its fucking huge...Erin wasn't lying'. I replied 'I'm glad you like it' and starting jacking it up and down for her. I pulled on my big balls with my other hand and thought to myself that this was the hottest moment of my life. Carrie just stared and kept whispering 'you are so fucking hot' and 'you are so fucking big'. I knew I wouldn't last long and said to Carrie 'show me your pussy'. She looked reluctant at first but then went even redder and spread open her legs. She was wearing a blue denim knee length skirt which she pulled up and exposed her yellow panties. I said again 'show me it' and she stared at me before slowly pulling her panties aside and exposing her hairy pussy to me.
Seeing my wife's older sister's pussy was too much for me and I told her I was going to cum. I pointed my cock away from me and in her direction and started to blow. She was sitting about 3 yards from me but my cum flew out and landed on the floor about a yard from her feet. It was a massive cum and probably the best I've ever experienced. She said 'wow...that was amazing...thank you' and pulled down her skirt and stood up. She then said she had better get out of here before my wife came home, and said to me that this will never be spoken of again. She hurriedly left and I noticed that she had parked out on the street rather than in our driveway and that that was probably why I didn't hear her pull up.
She drove off and I immediately started jacking off again reviewing what had just happened. I had always wanted to be caught masturbating, but always thought that I would plan to get caught deliberately and not by accident, and certainly not by my wife's horny older sister. I was imagining what she was thinking right now as she drove, and expected that she was heading straight home. I knew she lived about 20 minutes away and so I waited about half an hour before sending her a text message to her cellphone, saying only 'Are you at home masturbating?'. She wrote back 'god yes I am. That was fucking unbelievable. I am so horny.' Hearing that my sister in law is masturbating over me was really hot.
I wrote back 'Call me at home when you are about to cum'. She didn't reply but about 2 minutes later the phone rang and it was Carrie. She said 'fuck you have got me so horny and this is so wrong but I can't stop...I'm going to cum...please don't ever tell Erin...' and I replied 'that's it Carrie..cum for me thinking about my big cock...' and she screamed into the phone as she had what must have been an amazing orgasm. After about 30 seconds of moaning and cumming she said that she felt really guilty about the whole thing and that she wanted to go, and then said goodbye.
I came once more after she hung up but then decided to call my wife to see when she'd be home. I asked her how the shopping was going, and she replied 'good' and that she'd be home about 6pm. I knew I had the whole afternoon to jack off thinking about my wife's sister and how she had caught me masturbating and then cum over the phone for me. And that's what I did, replaying the horny events of that morning over and over in my head.
At 3pm, the phone rang again. It was Carrie. She said firstly 'Is Erin home yet' and I told her that she would be back at 6pm. She then said to me 'This is so fucking wrong but I cannot get that image of you jacking that massive cock and cumming all over the floor out of my head...I have been masturbating all afternoon thinking about it...I'm going to cum again for like the eighth time soon!' This was so hot. I replied 'Me too...tell me what you've ben doing?' She replied 'Oh god...just been sitting around naked at my computer looking at picks of big cocks and videos of guys jacking off on the internet...' With that she said she was going to cum again and this one sounded even bigger than the last. I was telling her she was a dirty slut who likes to suck and fuck big cocks as she orgasmed. After she had cum she said she was sorry and that this really was wrong and that she wouldn't call again and we would never mention this day again.
I have no idea what will happen in the future but I know that that Sunday was the horniest day of my life and I bet of Carrie's too.