Casey heard you and her step-mom talking last night about going to the doctor. She is worried, but you tell her it is just for a regular physical. She wants to know more. She sees a container and you tell her that it is for a sperm sample. Oh, it is THAT kind of physical! Since you have been so good to Casey, she wants to help you with that sample. Would you like that? Get yourself comfortable and get that cock out. Start stroking it and she will take off her clothes for you. Those little tits look so soft. You only briefly wonder how your 18-year-old step daughter knows so much about stroking dicks, but that thought passes as her ass is now in front of you. Her soft voice coaches you through a jerk session like you have not had in a long time. She tells you to pretend that her hand is the one stroking your cock. (You were already thinking that!) Casey asks you to tell her when you think you will be ready to give her that sperm sample.