The term 'BIG BEER BUY' can be broken down into three words: KEG (3 letters), CASE (4 letters), and BUY. A KEG is a large cylindrical container typically made of aluminum or stainless steel, which is used to store and transport beer. A CASE is a box or container that holds multiple bottles or cans of beer. Buying in bulk is a common practice for those who want to save money on their beer purchases. Therefore, the term 'BIG BEER BUY' could refer to someone buying a large quantity of beer, such as a KEG or a CASE.