What are "Random Boxes"? Random boxes are treasure chests. You can purchase them in the Itemshop and grab them from your Cash Items tab in the game just like any other cash item. If you right-click on one of your random boxes, you will - attention! - randomly get one of the items listed on the pages in this section.
Random Boxes can be traded or sold in the game if not stated elsewise. Furthermore, all of these pretty boxes include items you cannot get anywhere else, so if you're feeling lucky, you should grab some of them to acquire the special items.