There's a few machines like this in Spokane Valley, WA. Not that that the machine's operator is secret, but they have mystery buttons. It's been around for years and it's right outside a Coke distribution center(?). My siblings and I used to refer to it as, "The Mystery Magic Coke Machine"
https://www.google.com/maps/@47.6787458,-117.2733456,3a,49.5...