I was super horny one day so I went in my basement and was watching porn. My step sister and her friend were upstairs occupied so I began masturbating. I was stroking my fat cock good. I needed to bust a nut badly. I'm sitting on the floor right in front of the tv, pants around my ankles. Basement door was closed so I had no worries but to cum. I heard a laugh behind me and there they were, no way to hide it. My sister started with oh my god I can't believe it. I was trying to pull my pants on real quick., when her friend said don't stop on my account. You didn't get to cum did you? I say ok and my sister tells her friend lets go I'm so embarrassed by him. Then she tells my sister that she wants to watch and maybe lend a hand. My sister says omg I'm going upstairs. So I go back to jerking my cock and she is just staring at it. She says feels good doesn't it. Oh I was enjoying it so much. I asked if she wanted to help. She sat down right beside me and started squeezing g it hard and stroking it real slow, saying I want to savor your load. Must have been doing it for 30 minutes and I was gonna explode. When I'd get ready to cum she would stop and squeeze real hard. Driving me crazy! Then I hear my sisters voice say you are jacking him off. Her friend says you got to see this. Then I had my sister watching her friend getting that load. Her friend says to my sister you know you want to help to, so she sits on the other side of me and they take turns sometimes at the same time. It was so good. In the end my sister was saying cum for me and I shot the biggest load all over her friends tits. I loved it!