(Both my step brother and I were over 18)

One camping trip with our family (which rarely happened) we piled into my dads truck and headed to the lake. Once we got there my step brother told me to follow him so we could go “explore the woods”. We walked up towards the road that led into the campground. There was a small trail that went off to the side that led to a large culvert pipe that went under the road. He said “if we go in there no one can see us” It was big enough for us both to fit and and barely walk side by side. You had to climb up into this thing and once you walked back far enough, you couldn't see inside of it from the trail. We walked back and he pulled down his pants letting his already hard cock pop out. He made me suck him then pushed me against the wall of the culvert and fucked me for a while. It was really hot and I think of it every time I drive past it now which is pretty often in the summer.