"I drank the worm!" This disgusting boast comes from a recent visitor to Mexico, one who drank "real" tequila. But surprisingly, the worm does nothing for the liquor. A larval form of a moth that lives on the agave plant, the worm is actually a bad sign for tequila producers, indicating a low-quality product. But in the 1940s, tequila companies started deliberately adding a worm to bottles and telling Americans that the worm means the tequila is "real."