Adult jokes-Self examination

A medical professor was lecturing about self-examination of the breast and testicles. A female student asked another male student,
“Do you ever get an erection when you do a self-examination of your testicles?”
“Sometimes, yes” replied the male student.
“What do you do about it?” She then asked.
“Nothing, why?”
She thought for a while then said, “You mean you go around with a hard penis all day?”
“Err, no” he replied
“You mean a man’s penis will go down without having an orgasm?”
“Of course”
“I’m going to kill my husband!”