Yes, this was a real encounter!
A few years back, on a short visit to the Olympic Peninsula in Washington State I spotted this “Slow down” sign along a winding country road in the town of Sequim (pronounced Skwim). I sped up a little as I was driving past this place since I didn’t know whether this was a joke or for real. On the way back I noticed a man puttering around his front yard, so I decided to stop for a quick chat. Yes, he said, it’s real! His son loves to throw rocks over the fence! Then he invited me to come around the gate and check out the pile of rocks. I did just that, took a few pictures and then went on my merry way.