Starbucks Stack is a product from Starbucks that consists of a stack of cups and LIDS. The cups are made of plastic and come in a variety of sizes, while the LIDS are designed to fit securely on top of the cups. The cups and LIDS are sold separately, with the cups being identified by the acronym CUPS (4 letters) and the LIDS being identified by the acronym LIDS (4 letters). Together, these two components make up the Starbucks Stack.