Your primary doctor sent you in to be tested for a disease that he's been seeing more and more of lately. Part of the tested is that you have to jerk off into a cup for Me - the head nurse - so that we can run your sample in the lab. But don't be nervous! I make it so easy for you to perform, even under pressure. Soon you'll be forgetting all about the test as you excitedly stroke your cock for me. But no cumming until I say so!