Cock Lessons For My Step Daughter

My beautiful 18 year old step-daughter told me that she has only seen one cock and it scared her because she didn't know what to do with it. My wife was gone, and if you think I haven't jerked off thinking about her young tight body in a situation like this before you're crazy. She asked if she could see my cock, I know, I should have said no. But I just couldn't.