Clearly Jug is not really dead. But if Veronica and Archie are not in on it, why would Archie declare him to be dead when he checked his pulse? Of course, its possible that biology/anatomy are some of those classes that Archie never attends and he maybe actually doesn't know how to check for a pulse ( a skill that would seem to be invaluable in a town like Riverdale).
Maybe its a derivative of Jingle Jangle. Because in a town where teenagers run nightclubs, breweries, gyms, construction sites, and write long standing YA mysteries, why wouldn't there also be chemists thrown in there.