Abstract: A vessel closure system incorporating at least one hidden message is provided. The system includes a stopper reversibly occluding a vessel, and reversibly placing the vessel in fluid communication with an ambient atmosphere, in which the stopper has at least a first portion and a second part that incorporates a hidden message. The message may be humanly visually-perceptible indicia, or may further include stored, machine readable code. The message may be associated with any one of the surfaces of the stopper, or may be at least partially contained within a stopper void. The message may be included on a thin strip of material held between the stopper and the inside of a vessel neck. In some embodiments the stopper second portion may be envisioned as a type of “collar,” of many possible thicknesses, around part of the stopper first portion and the stopper portions may be adhered with an adhesive.