I was something like 18 and my sister was about 25/26. She was a looker and had an excellent body.

I was staying the weekend at her house - she was married but no kids. Her and her husband were out Saturday and I got bored and ended up naked wearing a black see through baby doll and matching knickers that were hanging on the back of the bathroom door.

I was in the bathroom admiring myself in the mirror and my cock was raging hard ........ so there I was knickers round my knees and wanking away oblivious to anything except my self pleasure.

I was on the verge of cumming ............ and at this point there was no going back - I"m sure you know the feeling - I was holding the baby doll up out of the way with one hand and feverishly wanking my cock with the other ........ my orgasm was building and the cum starting it"s way up my shaft ....... even if i stopped rubbing now I was cumming.

Then I heard a noise and a quick glance to my left - there she was - my sister, standing in the doorway watching! it was too late and I was cumming. the first spurt was imminent and try as I might to move I just had to keep rbbing and cumming - I tried turning away, dropped the nighti over my cock but I was coming and my legs were routed to the spot ......... I stared at her in disbelief and saw she was staring at my cock.

I looked down to see spunk all over the front of the nightie and my cock pulsing away - even without me touching it i was cumming and it felt so good .........

We both just stood there silent. I was completely at a loss what to do. She moved towards me stood a few steps away looked me in the eys and said "you dirty little bastard, get my things off!"

I didn"t even think I pushed the knickers down and pulled the wet nightie over my head ......... managing to get spunk all up my face and in my hair.

"you dirty little shit" she said ...... picking up her nightie "you dirty bastard. Get in the fucking shower and get yourself clean!"

And like the good little startled brother I was - I did as I was told and stepped into the shower. She was watching me like a hawk as I showered and could plainly see me through the glass shower door. Much to my distress I started to get a hard on again - for fuck sake my sister was watching me shower and I was getting a hard on!! She"d just watched me spunk into her nightie and things were now getting worse.

"well look at that you dirty little wanker, you"ve got a little hard on!" i turned away ............... "aww go on, wank it for me little brother, show me how you do it" and she smiled. I couldn"t beleive my luck ........ and stupid as I was I did as she said and stood there openly wanking.

I was looking down at my own cock as I wanked .......... I was so fucking horny and the soapy water made it even better. I looked up and saw she had her hand up her skirt and was moving her hand around - I guessed she was playing with herself - but at that age didn"t know much more than that.

This went on for about 5 minutes and I spunked again ............. I moaned as I came my cock was so tender, and then I heard her moan ....... and looked to see her eyes closed and her hand going faster under her skirt. She was out of breath and I just didn"t get what was going on. my cock wilted and she looked at me ......... she opened the shower door and much to my surprise reached in and grabbed hold of my cock and balls - hard and not very nicely ............ she squeezed and it hurt .............. her face up to mine she said "if you EVER tell anyone about this I"ll rip your fucking dick off you little wanker" and she gave my tackle a sharp painful tug. letting go she stored off leaving me gob smacked and confused ...........

I just got dressed and pretended it hadn"t happened. the rest of the day was just like it never happened and I wondered if I had dreamt it!!

That night I was watching telly with Gill and her husband. It was early evening and usually pub time ........... but Gill said she felt ill and said he could go on his own - "little Paul will look after me" she said ............... so off he went.

He"d been gone not 10 minutes when she stood up .......... looked at me and said "sorry about earlier Paul ........ really I am sorry, lets go upstairs and make up for it" - she held out her hand ................. and like a fool I took it and followed her upstairs.

In the spare room she let go of my hand ............. looked down and saw my cock was hard in my jeans already ......... she reached out and rubbed me through my jeans. "want to see my tits little brother?" .............

The rest is for part 2 - when it gets really interesting!!