Sweetie. Step-mom needs to discuss something important with you. You're going to be getting a medical check-up tomorrow. Yes, I know you're nervous and step-mommy doesn't want you to be. I think it would be good if we go through what a check-up looks and feels like, that way you'll be ready. Since step-mommy is a doctor, step-mommy can help. Now you will need to get naked so step-mommy can check your penis and testicles. Then step-mommy will check your prostate. What's a prostate? Well step-mommy will explain while I'm massaging it. Looks like you have a good healthy erection too, I'll just go ahead and milk you sweetie so step-mommy can get a sample of your sperm. Good to have a baseline.