I know it's nasty, but I had this thing for my son's girlfriend and she didn't seem to mind, and well... things just sort of happened.

Up until Brad started dating Jennifer our life was pretty normal. Sure, I knew that my son was a little more attracted to me than was normal. I'd realized that he had erections when he'd seen me in various states of undress over the past few years.

But even though deep down in my darkest thoughts I had fantasized about making love to my son, I certainly would never do anything about it.

I was a firm believer that everyone had perverted thoughts from time to time. I often wondered what middle- aged fathers were really thinking when they were in the act of kissing their pretty young daughters. I know what I usually thought about when I was kissing my son for one reason or another.

But when Jennifer came home with Brad one night and he introduced her to me and we performed the ritual cheek kiss and hug, I was surprised by the feeling of warmth I experienced.

I don't mean warmth in the sense of fellowship. I mean one of those heart rate, wet pussy, prickly skin feelings of warmth. Jennifer reminded me of myself when I was her age. Actually she could have easily been mistaken for my daughter.

That first time I was confused and embarrassed and I noticed the smug look in the teenage girl's eyes. But I got over the feeling and composed myself and then the kids went out on their date and I tried to forget the incident.

Both Brad and Jennifer had just turned 18 and were both graduating from high school in a couple of months. They seemed deeply attracted to each other so when I heard noises up stairs one Saturday afternoon just after arriving home from the store, I knew what was happening.

I was worried, I hoped that they were practicing proper birth control. Even though I liked Jennifer, I thought that both her and Brad were too young to get married and especially too young to have children.

As I continued to hear my son's bed squeaking and the headboard bumping against the wall of his room in a steady rhythm I became more and more nervous. What if they were ignoring birth control? I knew how passion could over power teenager's common sense in the spur of the moment, and I really didn't want to risk being a grandmother at 40.

With no real plan of action I climbed the stairs to my son's bedroom. As I crept down the hall the image of the two kids making love kept running through my mind. The image of a "young me" screwing my son in the heat of passion.

By the time I reached my son's bedroom door I was breathing harder than I normally would have from the climb. I pressed an ear to his door and listened.

I could hear muffled voices, first a female voice then a deeper male voice. I couldn't understand what they were saying but when I heard a muffled female moan of pleasure I knew that Jennifer was enjoying my son's efforts.

I knew that I should have waited till later but I gently pushed open the door and peered in. What I saw pushed thoughts of birth control and motherly concern right out of my mind.

Jennifer was on top and she was "riding" my son like a cowgirl riding a mechanical bull. Neither kid could see me from my angle, but I could see them perfectly. My son was stretched out full length with his feet toward me and Jennifer was rising and lowering herself on his big shiny dick at a fast rate.

It was as if I was in a dream. I watched fascinated as Brad's dick appeared and disappeared to my view and Jennifer's motions increased at an even faster rate.

It was so sexy looking; watching my son plugging into Jennifer's pretty young body, to see his legs straining with need as he humped his crotch up against her as she ground herself into him.

I could imagine how it must be for them. I could perfectly imagine the feelings Jennifer must be receiving from my son's full erect cock as she sank down onto him. I was soaking wet and my heart was in my mouth as I watched on, unable or unwilling to move.

Then Jennifer groaned and her strong young body seemed to shiver and she leaned forward and uttered a gasping, "God, Brad. I love you." Then she slumped down on him as if in exhaustion.

As I silently closed the door I heard my son say, "Okay baby, now it's my turn, roll over and lets see how long I can last."

The fear came back to me again, over powering my lust. He hadn't cum in her yet, but he was going to. And I had seen them fucking and knew he wasn't wearing a rubber. Damn, what could I do?

I knocked on the door. Then I opened it and walked into the room. Both Brad and Jennifer were struggling to cover themselves with the disheveled bedclothes.

"Children," I said, "I hope you're using birth control." There, I'd said it, and I was glad I had because as stupid as it might sound they hadn't been. Brad's big plan was to pull out at the last moment and cum on Jennifer's belly.

Apparently the kids had been doing if for a couple of months whenever they had the chance. I was glad that I'd nerved myself up enough to burst in on them. God, what a disaster if Jennifer had gotten pregnant.

It turned out that Jennifer hadn't bought pills because her mother was very religious and believed that people should never have sex until they were married. She hadn't gone to her gynecologist because her mother would have found out.

I know that it wasn't my right, but I gave Jennifer my birth control pills and told her to start taking them right away. My husband was on the road so much because of his new job that I wasn't expecting any action for a few weeks at leas and by that time I could get more pills and hopefully get Jennifer sorted out.

As it tuned out my plan had a few flaws in it.

That night I heard Jennifer and Brad at it again. I ran up to his room and rushed through his door yelling, "You can't have sex until Jennifer's been on the pill for a couple of weeks. STOP!"

Both kids were shocked by my intrusion, but this time even though Brad pulled the sheets up to cover himself, Jennifer didn't. she just lay there naked resting on her elbows and looking up at me.