My step daughter used to walk around naked in front of me...but the real fun began after she turned 18 but still lived at home while going to college, like what happened in this story.
I remember driving home from my dads house late one night. It was just me and my step daughter in the car and I can't remember why it was just us. It's a little over an hours drive to get home and I was ocassionally patting her leg as we drove along.
Sometimes during the drive I started getting a little hard so just for fun I somehow managed to pull my cock out while continuing to drive. I don't know if she saw me do it as it was very dark in the car. She didn't give any indication of knowing what I did so I gently took her hand and placed it on my cock.
Without saying anything, she started gently rubbing it. It was more like she was exploring it than anything but it did get me really hard. At this point she began a slow and gentle stroking of my shaft. I was in heaven for the next several miles until I could take it no more.
I pulled over and sat in silence letting her rub me off, I came so hard. Afterwards I tucked it back into my pants and we finished the drive as if nothing happened.