I don't know what "worm of the still" means, but it could be a reference to the custom of having a worm in a bottle of mezcal.
Mezcal - Wikipedia, the free encyclopedia
It has to do with alcohol distillation, do you know what it is? :)
Well, it has to do with the apparatus of a distiller, albeit a very old one I presume. Here: feeverte.net/dicksdistillation.html
"This process of evaporating and condensing a liquid is called distillation; the apparatus is called a still or retort, and the coiled pipe is the "worm of the still," or the condenser."
This [Worm of the still] is a long tin pipe, bent in the form of a screw, and enclosed in a copper or wooden vessel full of cold water.