If you are completely flummoxed by this cartoon, that just means you're not reading the comments attached to these entries, which generally are more edifying than the entries themselfs. By way of explanation, what I was trying to get at in this illustration, the core concept if you will, is how hard it would be for an earthworm to rob a convenience store, possessing no means by which to communicate with humans. Maybe they have a language amongst themselves, such as writhing in a certain way or releasing pungent pheremones, but these missives are lost on humans, especially on convenience store employees.