One night while browsing on my phone, I felt a little horny and decided to look up porn to get more in the mood before bringing myself to orgasm. It took no time. I was wet and achy and in need of a good orgasm. I flipped over on my back and started to massage my pussy. God, I needed this. My husband has been too tired to fuck me for the past several weeks. So I really needed to get off before the sexual frustration became too much. But suddenly, while I was really getting myself closer to coming, I saw my step son peeking through the door watching me. I called out and he retreated down the hall. I then yelled for him to come into my room to scold him for watching me. It turns out he's been watching me in the past. I don't know how, but he always seems to be able to detect when I am going to masturbate. Feeling awkward but still horny, I agree to finish what I started and let him watch while he strokes his cock.