On Thursday (In Two Days) I am having a physical exam. My problem is that I'm really nervous. What if I had an erection during the exam when the doctor is checking if I have hernia.
Doctors should be mature and professional. If you get an erection, he would probably ignore it. I suggest you think about random, non-sexual things though. Some of them would be Games, Cars and Mathematics
I usually use the last one when teacher calls on me in class to answer a question. Thinking about maths loses my erection in less than 10 seconds.