The cache is located in a small public park with pic-nic tables and playground equipment for kids.
Joe's Diner is a placeholder name for a fictional or hypothetical everyman's restaurant. Although there are franchises that use the name, its rhetorical use is often to describe a small, local business contrasted against large businesses or franchises. The phrase "Eat at Joe's" is a complementary fictional or hypothetical typical advertisement for such an establishment,