An apparatus for adding a secondary substance to a primary liquid within a sealed container, for example, a shot of liquor to be added to a can of soda. A secondary container contains the secondary substance preferably a liquid and has a frangible seal. A mechanism sealingly and mechanically attaches the secondary container to the hull of a primary container having primary liquid. A frangible seal is provided to the secondary container. A penetrator is disposed at least partially within the housing of the secondary container and is at least partially surrounded by the attachment mechanism. The penetrator causes rupture of the seal and mechanically penetrates through the hull of the primary container. The substance from the secondary container mixes with the liquid of the primary container. The secondary container may attach to the top, side, or bottom of a conventional primary container, a soda can.