You've come in for an exam to check your sperm.
I put on some gloves and a condom on you as I explain everything.
I begin stroking and licking your cock while teasing you with my body, encouraging you to cum for me.
I strip my clothes off and keep explaining what I'm doing and why.
After you've came, I remove your condom and instruct you to dump it into your mouth, because it's vital for your health.