What do I do when a male patient gets during a physical examination?

I'm a 4th year medical student from Cairo. We train in a clinical setting twice a week. My job is to see patients before their consultation with the surgeon. I usually carry out a physical examination which includes taking their pulse, using a stethoscope to check heartbeat, measuring blood pressure, testing reflexes, and etc. The patient is always fully clothed. I don't understand why sometimes, well, I noticed that a few of my male patients, get . Its a awkward situation, Do I just pretend not to notice it?