A connector useful for combining the contents of a pair of containers which includes a hollow body for passing fluids between the containers. The body includes top and bottom end portions dimensioned to receive open-ended containers in an interference fit. The top end portion includes one or more recesses sized and arranged to facilitate drainage of a fluid from the first container into the second container when the first container is positioned above the second container. A middle portion is positioned between and adjoins the end portions of the body. A system for combining the contents of a pair of containers is formed when containers having substances to be combined are fitted onto the end portions of the connector.