DISCLAIMER:- The following text is sexually explicit and contains depictions of sexual acts that have been classified by the surgeon general as potentially dangerous and unhealthy. You must be a broad minded adult to read the text, and you must not make this text available to minors or to any person who does not wish to view it. Unprotected sexual relations with unknown partners is hazardous and we urge the use of condoms and safe sex at all times.

My sister who is eighteen came home one evening drunk and was not capable of getting to her bedroom.Our parents were away for the weekend so I thought I had better help her to bed.When I eventually got her into her room she started to try take her dress off and was totally unable to unzip it.

I obliged and quickly had her out of the dress standing there in just her panties and bra. She thought I was her boyfriend and kept calling me by his name.She pulled me against her and wanted to know why I wasn't taking advantage of her.She then pulled her bra down around her waist and tried to push her panties down.

So by this stage I decided to have a bit of fun with her and see how far I could get if she thought that I was her boyfriend.I got her out of the undies and she immediately flopped down onto her bed, shut her eyes and passed out.By this time my cock was ready to burst out of my pants. She had a magnificient body and I reached and fondled her breasts.

There was no response as my hand drifted down and slipped between her legs. Then her legs parted and there it was - her cunt just waiting for little brother.I carefully mounted her and she immediately sighed and then passed out again. I pushed inside and had my fuck.

It only lasted 30 seconds and then I withdrew as I didn't want my cum all over her bed.

Next morning she had a real bad hangover but was obviously totally unware of me having fucked her. Thing is now she's pregnant, she says she's only had sex twice with her botfriend and both times they used a condom. I'm still wondering if I should tell her or not?