It was a hot summer day in late May. This summer would be the hottest on record for sure I thought as I just got in from a morning of doing yard work. I just went to sit down in the A/C and watch some TV when my wife came up from the basement.

"Get over to my Mom and Dad's house and put the window air conditioning units in for my sister," she ordered.

I looked at her thinking are you serious...

I just nodded and put my sneakers back on and went out the door back into the heat to do the task.

My in-laws lived in town and my mother-in-law was out of town and so was my father-in-law. My 19 year old sister-in-law just finished up her first year of college and was clueless when it came to this stuff. Plus she could not lift the big window units by herself.

I arrived at the house and walked in the front door. I thought to myself how the hell can it be hotter in here than it is outside. I hollered for my sister-in-law as I walked in the door, "Mandi where you at."

She hollered, "Be right up."

I figured she was in the basement which was probably the coolest place in the house.

I heard her come up the steps and when she rounded the corner I was shocked. There she was wearing one of the smallest green bikinis I had ever seen. She looked amazing. She was maybe 5' tall and if she was 100 lbs soaking wet I would have been shocked.

Her curves though looked amazing and her 34D chest was begging to be released from that skimpy bra top.

"Thank God," she said, "it is so fucking hot and as usual my parents did not think ahead."

I told her it was not a problem and to just show me where the A/C units are and I will take care of it.

She said, "Follow me upstairs."

I was happy too and was sure to stay far enough behind her so I could see every curve of that ass and those legs as we walked up the steps. It was almost like she was swaying a little more knowing I was getting a look I had never gotten before.

When we got up stair she explained that all 6 of the window air conditioning units were behind the walls in the storage areas. In a Cape Cod style house it was hotter behind the walls and harder to get things out.

I started taking them out and walking them from room to room and up and down the steps. I finally got all 6 in leaving Mandi's room for last.

I turned the A/C on in her room and sat down on the desk chair in her room exhausted. I was resting for about a minute when she walked in with a glass of ice water. She put the drink down on the desk and gave me a hug.

"Thanks so much it was horrible in here last night," she said as she walked over and sat down on her bed.

I looked over her body and noticed her large nipples were beginning to become erect from the cold air. I could not help fixating on them every time I looked at her.

I said, "It must have been. It was like 90 degrees last night with humidity and all."

She smiled and said, "I know, but you are my hero."

We kept making small talk and I finished my water. I did not notice, but from looking at her body in that bikini I had a little bulge in my shorts, and I got nervous and knew I could not get up. Mandi then asked, "You want more water."

I said, "No I am fine."

She got up and walked over to me and took a piece of ice out of my cup and went back over to her bed and sat down rubbed on her neck and said, "Boy it is still hot in here, this ice should do the trick.."

I thought to myself she had no idea, as I got harder. This time I saw that she was looking below my waste and noticed my predicament.

She continued to rub her neck with the ice as we continued to talk. Finally, she said, "So why don't you get up and close up the wall and get going."

I said, "In a minute," trying not to look too uncomfortable.

"Oh come on John how else will I get a better look at you if you won't get up and walk around for me."

I was shocked to hear her say this. My shock wore off when I noticed her getting up and walking towards me. She had purpose in her eyes and said, "I can tell you are hiding something very special there, and I wanna take a look."

With that she reached down and tugged at my shorts. I stood up and she dropped to her knees. My now semi-hard 10” cock flopped out as she tugged my shorts off. The look on her face was priceless and she said, "Are you fucking for real."

I took my cock in my hands stroked it a bit and smacked her face with it and said, "This is very real baby."

With that she began sucking me hard and fast like it was the only cock left on earth. She messaged my balls and stroked my staff like a porn start. I thought damn if I had known this about Mandi I would have never looked twice at her sister.

After enjoying Mandi's mouth for a while I reached down and began to message her huge tits. She moaned while sucking my cock, and I thought I was going to blow right then and there. So to save myself I pulled her up and threw her on the bed.

I removed her top and bikini bottoms and slid up her body and kissed her passionately. I then kissed down her body paying special attention to her nipples as I worked my way down to her nicely shaved pussy.

I went to work on her clit with my tongue and finger fucked her with two then three fingers, ramming them in and out of her wildly. I then slipped one finger in her ass driving her nuts. She screamed and yelled and pushed my face deeper into her beautiful womanhood.

"Oh John you are gonna make me cummmmm."

With that she exploded on my face and bucked harder and faster as she filled my mouth with her orgasm.

I could tell she still wanted more so I got on top of her and slid my 10" cock up and down her slit. I said to her, "Beg for it baby."

"Oh John fuck me hard with that massive cock. Show me what my sister gets every night."

With that I began fucking her with the entire length of my cock. Slamming her and making her tits bounce all over.

Somehow she ended up getting on top of me and riding my cock while I sucked on her massive tits. She could move those hips and really make a guy see stars.

I was close to cumming and knew it so I pushed her off of me and began to have her suck my cock and she held her tits together so I could fuck those massive jugs.

She looked up at me as I had that look in my eye and said, "Let go John. Shoot your cum all over my face and tits."

With that I exploded, shot after shot of cum spewed from my cock all over her. She moaned and said, "Oh baby it is so warm and salty."

I collapsed and she licked my cum off her tits and face.

I looked at her and she threw my shorts at me and said, "You better get home you bad boy before I have to tell my sister what we did this afternoon."

I shot her a bit of a worried look, and then she crawled up next to me with that tight little naked body and whispered in my ear, "Don't worry this is our little secret, and it does not have to be the one and only time unless you want it to be."