My boyfriend, Tommy, works off shore on the oil rigs. He works for two weeks and then has two weeks off. So, obviously, every two weeks out of four I'm on my own.

Since meeting Tommy some two years ago I've become great friends with his sister, Liza. When Tommy's away she usually comes around with a bottle of wine for a girly chat and a general natter. Unlike me, maybe that's why we get on so well, Liza is a complete extrovert, a total scatterbrain, but great company and a great laugh.

Occasionally, if she goes out with her boyfriend she'll invite me along. And sometimes, not always, I'll go. Anyway, last week she said they where off for a drink and invited me along. It was a beautiful Summers day, so I went.

Liza is a gorgeous looking girl and since I've known her she's had lots of boyfriends, most of them really hot. But, the latest one, Kevin, just didn't somehow fit the bill. He's a bit of a nerd really, skinny, wears glasses, not in the least bit nice looking, even his clothes are a bit on the scruffy side, yet, they have been together for over three months, a record for Liza.

The third bottle of wine was, definitely, a mistake. So when we got back to my place Liza and I were more than a bit tipsy. I opened more wine and we sat down. I have two matching sofas which are opposite one another. Liza and Kevin sat on one, me on the other. Liza was, as usual, behaving outrageously, but we were all having a great laugh. Suddenly, Liza did something she had never done in front of me before, she leaned over and playfully bit Kevin on the ear. It was all a bit embarrassing for me, even more so when Kevin turned his head towards her and she kissed him, passionately, her tongue down his throat. I squirmed a bit and sought of mumbled something about maybe it was time for bed. But, then Liza did a very weird thing. She broke away from Kevin, took hold of my hand and said very seriously, "It's ok to go to bed, but if you like you can watch!" I get embarrassed very easily, I must have blushed six different shades of red, looked down at the floor and shook my head. But, when I looked back up Liza and Kevin were into it, kissing intensely. So I stayed and I watched and, god forgive me, I have never been so turned on in my life.

The kissing soon led to the boob feeling. Liza was, obviously, really up for it as her nipples stood proud through her summer frock. And then, in almost a frenzy of excitement she took hold of him, kissing him madly. Kevin threw his head back in a long moan. But, she unzipped him and that's when I saw it. Maybe, it would have looked ok on a six foot black guy? But on this little runt? Well! I can only say that Kevin is deformed. His cock sprung out like something that had been computer enhanced on a porno channel, I couldn't take my eyes off it. It wasn't so much the length of it, although it was long enough, but the thickness, my god, the thickness about the diameter of a beer can. Think of a packet of Pringles, I'm exaggerating a little on the length, but you'll get some idea. And now I understood why the relationship had lasted so long, this guy was hung like a donkey. Liza slid down, half smiling at me, I blushed terribly, as she took hold of it, her fingers barely going round half-way. She must have known, probably from past experience, that she couldn't get her mouth around it so she licked it and Kevin's hands formed fists as he moaned loudly. I desperately wanted to touch myself but, despite my excitement, I just couldn't bring myself to do it, there, in front of them. So, I sat on my hands and watched. Liza was up on her knees now, straddling him and wanting it. She lifted up her skirt, typical of Liza she wore no underwear, Kevin slid down and, with a huge moan, she pushed her crotch into his face, pressing in his head with both hands. I watched, fascinated, as her buttocks clenched, her body arching, again and again. But now, in almost a frenzy, she broke away and I saw something that I swear should have been impossible. She took hold of this massive cock from behind and positioned the end on her now very wet hole. Very gingerly she eased herself down. Nothing happened at first, but then her c**t opened, like a large mouth and the head disappeared. She threw back her head and moaned, then ever so slowly, carefully, she lowered herself on this massive cock. It was unbelievable as it slowly disappeared inside her. And, again very slowly, she lifted herself up, her c**t lips pulled out like a large doughnut as it slid along his prick, the cock glistening. And so it began slowly at first, pulling out almost to the tip, moaning, moving in unison and then as the excitement increased Liza stayed with him the cock buried inside her she rode him like a horse. I have never been so turned on and I was desperate to touch myself. Still sitting on my hands, even then I'd be mortified if they were to see me, I opened my legs a little. My knickers were soaking, I managed, from beneath, to touch myself through them, and I watched.

Kevin came first pushing hard again and again deep into her. Liza was desperate now, and so was I, lifting herself up and, almost obscenely, large globules of his own cum and Liza's wetness slid down his shaft. I pushed my finger under the gusset and my clit slid around like a wet piece of soap. I think we both came together, Liza moaning loudly like someone demented, me biting my bottom lip but really wanting to scream like her.

Feelings of guilt and embarrassment afterwards and terrible thoughts of Tommy somehow finding out. But, by far, my best orgasm ever. I dream of that cock.