My stepsister and I have always been very close, but lately she has been getting... even closer. I love it when we are touchy with each other, but she has NEVER touched my dick, until today. She asked me for a back rub, rested her head on my legs, and before I noticed, she was ready to pounce on my dick! I jumped from the couch the second I realized what was happening. There are lines we shouldn't cross - yet I wanted to. The problem is that she didn't stop there. She begged me to help her gain some "experience" because she didn't know how to fuck. I couldn't believe she was touching my dick! But I have to say, she was a natural. Who knew my stepsister could ride a cock like that?!