Teamster's Rig is a term used to describe a SEMI-truck, which is a large vehicle used for transporting goods and materials. It is typically driven by a professional driver, known as a TEAMSTER, who is responsible for the safe operation of the truck. The term 'TEAMSTER's Rig' is derived from the fact that the driver is a member of a labor union, such as the International Brotherhood of Teamsters. The SEMI-truck is usually equipped with a trailer, which is used to carry cargo. The size of the trailer can vary depending on the type of goods being transported.