"In the bag" usually means "as good as done", or it could mean someone is intoxicated. For example, "Look at this new crop of GOJAC caches! John must be in the bag again". Well, you'll find another meaning here.
I was out hiding a few caches today, and once again, I found some surprising spots. This is one of those spots, and I don't believe I've seen another like it. At first I thought it was some sort of memorial, but as I approached, its purpose quickly became clear. Are there leagues for this activity?