I believe he is making a joke regarding the practice of consuming drugs via intravenous injections, also commonly known as "shooting up." The precipice of the joke appears to be the expectation that when one "takes neither and shows up drunk", and the twist is that "rather than showing up drunk he's doing hard drugs such as heroin, cocaine, or even methamphetamine or other commonly shot drugs" wherein lies the humor. Though that is simply my interpretation, and perhaps the original poster will be so kind as to elucidate, we shall see.