When I was 20, I was either coming out of the bathtub or going into it, when my girlfriend let out an excited, "Oh my God! What happened to your penis?"
I looked fearing to see a rash or teeth marks, but nothing was amiss. It turned out she had never seen my foreskin before, as that was the first time that my cock was naked and soft in front of her. I pulled back my foreskin, and she recognized her old buddy. From that day on, sometimes when we out in public or hiking, she would ask me to pull out my cock, so she could see my soft cock and foreskin, before the looming erection retracted my extra skin.