Big ass step sister watches her muscular stepbrother masturbate and she wants to join in

I'm bored at home and I remember that my stepbrother is in his room so I go and find the surprise that he's masturbating and I can't help but see his big pink cock so that makes me horny I start touching myself but I get careless and he notices I'm already so horny that I tell him I can help him with my tight pussy and he accepts without hesitation leaving his cum on me.