By the time I turned 19, my girlfriend and I were already 1 year together. Our relationship had a lot of flare, and she was always getting freaky everywhere we went. We had already done it in the beach, her house, my house, movies, and the mall, but never the park. One day we were at the park close to her grandma's house around 8pm where everything was dark. We were already in the car when she started climbing up on me and taking my shirt off. She was really getting into it, since there was no one parked beside us. There was only one car but nobody was in there. As she was riding on me, moaning loud and all, I heard a loud thump that scared me. We both went down thinking that someone was going to see us. As we were lifting up our heads slowly to see outside what was causing the noise, I noticed that the car beside us was rocking back and forth, as if someone was really getting it on in there. We tried to see who it was, and my girlfriend was the first one to burst out with a scream of disgust. As I narrowed my eyes to see better who it was, I finally noticed that the couple in the car next to ours was my girlfriend's grandparents. I started laughing so hard that they heard me and they stared at us with great shock. At that moment all of us had our eyes wide open, having a very awkward and embarrassing moment. I will never forget that day. Now days, I always make fun of my girlfriend when we're about to have sex.