A stackable block is provided which may be constructed as a traditional toy or as a beverage container. The block includes six sides. Furthermore, the block includes at least one projection which projects from one of the block's sides. Each projection is square so as to include a face and four sidewalls. Furthermore, it is preferred that each projection include a ridge forming a recess between the square projection's face and a block's side. Furthermore, each block includes at least one slot formed into one of the block's sides. This slot extends the entire side of a block and forms an elongate cavity sized for receipt of a projection. Preferably, each slot includes parallel opposed flanges sized to project into a projection's recesses.