Last week I let my step dad watch me masturbate, knowing he too was wanking. I was lay on my bed naked fingering my pussy and playing with my clit, when I caught sight of him watching me through the half open door. When I realised he was masturbating I decided not to shout out, but to carry on and let him watch me cum. Opening my legs wide so he could get a better view, I put two fingers inside myself and frigged my clit fast and hard. My step dad came first as I heard him groan, then knowing he was still there I brought myself to a really strong climax. As he was about to walk away I said "Hey, John thanks for watching". We haven't said anything to each other since because of my mom, but each time I've left my used panties on my bedroom floor since, I've found them later full of gooey cum.