I just read elsewhere -- in the just-refreshed thread about Sing Out! magazine, which includes some discussion of Tom Russell and this song he co-wrote with Ian Tyson -- that "whiskey toast" means rye toast. Undoubtedly, this is occupational terminology among diner waitresses and short-order cooks. Makes plenty of sense once you're clued in, but I might never have figured it out on my own.

Ian apparently wrote the song near-complete, and then Tom added the "aye, aye, aye" vocal riff while singing along and thus gets credit for creating the chorus in its fully-developed form.