You Like To Watch, Step Bro?

Your step-sister has just got in from her night out... And you're just getting up! The second she gets in she begs you not to tell your parents, but you'll only keep quiet if she does something for you in return... You've always had a bit of a thing for your step-sister, so you tell her that you want her to instruct you to WANK in front of her! She'll do it, but she wants to WANK aswell! Better hurry, Mum and Dad are getting up soon.