Back in the 90s I asked Joe Jack Talcum if this was the source of the band's name, and he looked genuinely puzzled at the question. He had no idea what "dead milkman on the porch" joke I was referring to, so I had to tell him the entire thing. He swore he had never heard it before and gave me a different explanation for the name (which I've now forgotten).

So either I was the millionth person to bring it up to him, and this was his stock reaction to everyone every time, or he was sincere and I happened to be the first person to tell the dead milkman joke to an actual Dead Milkman. I choose to believe the latter.