So I recently found out that I can cum from just rubbing the underneath of my tip, playing with it like a clit!  Yesterday I was on the sofa with my partner and I was so horny, she was wearing some tiny little shorts with no knickers and I could just about see her pussy when she had her legs in a few positions, I had joggers and boxers on with my hand in them, soon enough I started wanting to cum, so I asked if she was up for any fun, no! Ok so I decided to try cum without her knowing. So l