Watching my ex gf and her son fuck...she used to walk through the house at night with a sheer nightgown on and her nipples were clearly visible and I'd see him staring at them when she wasn't looking. She was very sexual and I think she got a thrill knowing he could see her tits....so I like to imagine him coming up behind her and reaching around and softly massaging
Her tits and her reaching back and feeling his hard young cock and leading him to the bedroom ....
I had an ex that I wanted to watch give her son a blow job. I told her this once when we were having sex. she said it made her hot to think about it but it was never going to happen...but she did enjoy me describing it in detail when we fucked