Lanterns On The Lake , Widowspeak, Saintseneca, Surf Rock Is Dead, The I Don't Cares
is just that, an expletive intended to impart disbelief, like pshaw,
ptttttt, and similar. Humbug is a load of malarkey, an untruth, a fairy
tale, a line, a fish story, a made up story, a deception.
The latter interpretation is derived from the word's association with Ebenezer Scrooge, a character created by Charles Dickens.