There is only one more Who Knows Where, which is a bed that will lie near the cauldron and the Pipe. You get it near the end of the game if I remember correctly, but I don't recall exactly after which level you get it. A lot of discussion exists on the internet about the Outhouse and the mailbox but no one knows what they do till now, most opinions defend that they're just for humourous content, some believe the mailbox is meant for future DLC's, while the company director already revealed that they are actually not thinking about extending the game anyhow since they feel the game is complete as it is.. I guess we'll have to see what comes..
