Ivy "Wank in Secrecy"

You know your girlfriend's sister is home alone at the moment, and you can't help but fancy her and want to spend some alone time with her. But you've just caught Ivy coming out of the shower and her towel drops to the floor where she's shocked to see you. She can't believe you've just seen her naked! But you tell her you liked what you saw and before you know it, you're both wanking together, but this has to stay a secret!