If the singer had Bacchus's wine cask he'd drink all day at no cost. And to avoid drinking alone he'd bring a friend. But since he does not have it, "let's drink like honest men." Let Bacchus have his wine; whisky is more divine.
Bacchus (seemingly a Lydian name) is the God more properly know as Dionysus -- who was of course the god of wine and drunkenness -- and also of orgaistic rites; he was accompanied by the satyrs and Maenads (Baccae). He also had fertility aspects, which explains the idea of the bottomless wine vat.
Richard Alfred Millikin is better known as the (probable) author of "The Groves of Blarney." - RBW