Among the specialized types of Late Classic Maya vessels (a.d. 550–900) are small bottle-shaped containers known as “flasks.” Current interpretations of their uses, for example as poison bottles or medicine bottles, are speculative. In some cases, such interpretations rely on analogical comparisons with other Native American containers based on their formal similarities of shape or construction. This paper presents research on basic construction methods of flasks, a set of correlations between the various social mediation roles in which such flasks are depicted in Classic-period artwork, their material correlates (the vessels themselves), and a report of their specific contents. We also provide evidence of the first discovery of nicotine in an ancient Maya vessel, which is the first empirically demonstrated proof for the presence of tobacco contained in a clay vessel from this cultural tradition. The codex-style flask yielding this evidence bears a text that appears to read yo-'OTOT-ti 'u-MAY-ya, spelling y-otoot 'u-mahy “the home of his/her tobacco.” This is only the second case in which residue analysis has shown a Maya vessel to hold the same content as is indicated by a hieroglyphic text on the same vessel.