If you’re riding the “gravy train,” you’re enjoying ease, success, or profit, particularly if it’s undeserved and somebody else is paying for it.
Gravy is a delicious, rich, fattening food, and the word is frequently used to describe luxuries or large amounts of money. It can also mean obtaining a windfall, such as an inheritance or a lottery prize. Related idioms are “meal ticket,” “easy street,” and “easy money.”
The term riding the gravy train may have originated from phrases such as “everything else is gravy,” which people have used to describe a large profit after expenses.
The term could also have come from 1800s railroad slang, though it didn’t appear in print until the early 1900s. W.C. Handy used it in one of his blues songs written in 1914, in which he bemoans falling off the gravy train.
The Encyclopedia of Word and Phrase Origins by Robert Hendrickson says that in the 1920s, railroad men used the expression “ride the gravy train” to describe a run on which there was good pay and little work.
While the phrase arose in America, where railroads were so important in uniting the country in early days, etymologists say there’s no evidence to support it arising from railroad lingo — none of the known appearances of gravy train refers to a literal train.
However, “gravy” has long been used as slang for something easy or cushy, simple to do, or an unexpected benefit. This is recorded in the major reference books as appearing slightly earlier (1910) than “gravy train,” which didn’t show up until 1914. “Gravy” in that sense appears in the Courier of Connellsville in November 1895, almost two decades before the previously oldest known example.
Another theory is that the phrase originated among vagabonds who hopped trains as a way of life and for whom “gravy train” would be a likely metaphor for an easy existence. That is, if you can believe that the hobo life was “an easy existence.”
The term was used in a Pink Floyd song called Have a Cigar:
Come in here, dear boy, have a cigar,
You’re gonna go far,
You’re gonna fly high,
You’re never gonna die,
That would be the ultimate in gravy trains, all right!