So this happened to me when I was fifteen. Me, my mom, my dad, and my sixteen year old sister were on vacation down the shore. My mom heard of a nude beach nearby and decides it would be fun to go. In the morning she woke me up and told me to just bring swim trunks and a towel since we wouldn’t be wearing anything else. I was nervous but my mom forced me Togo along with the rest of the family. We got there and we got out of the car. My mom and dad started to undress. It was obviously gross because they are my parents. I noticed how big my dad’s penis was. This is the first time I saw it and really remembered. It was huge compared to mine and more hairy too. My penis wasn’t small, but it was just barely below average. My mom told me and my sister to get nude. My sister was pretty (she is but not in a sexual way for me). I knew that it would be super awkward,but I just accepted and pulled off my shorts. I almost immediately got erect. We walked down and set our towels up. I was kind of covering but my mom told be not to worry because everyone was nude. I decided to go into the water because I would be covered. I was swimming with my sister for awhile and thought it was about time together out. The only problem was shrinkage. The water was cold. I was walking quickly so no hot girls would see me. Sadly my sister grabbed my arms and held me out for a group of girls to see my penis. They were laughing and commenting about its size as I tried to get my sister to let me go. I pushed and she fell in front of me pulling me down with her. I was sitting on top of her. My now hard penis touching her body. We were both frozen out of shock for a second before she grabbed my balls and squeezed them to get me off of her. Iran back to the towels and she soon followed. We both never talked about that experience ever again.