Family Affairs. Taken hard by the stepson

I'm lying comfortably on the couch, zapping through the TV programme, when suddenly my stepson comes into the living room. He sits down on the couch, talks to his girlfriend on the phone and obviously doesn't mind at all that I'm watching TV. Of course, I inevitably overhear his conversation and I don't like what I hear at all. When he hangs up, I tell him off, but he doesn't seem to be interested. I keep talking to him until he suddenly stands up, opens his trousers and shoves his cock in my mouth. I vacillate between horror and excitement...