Many people have likely heard people say things like, "So, you're riding the gravy train." This phrase is generally used interchangeably with terms like "sitting pretty," or "living on Easy Street." It means that a person's life looks good and seems to be pretty easy, as far as the speaker is concerned. People may feel that the subject attracts opportunities or that things just fall in his lap when they use the above phrases in reference to the individual's life or business.
The term gravy train also refers to obtaining a windfall. Another related idiom phrase is "meal ticket." An heir who has inherited a great deal of money or a lottery winner may be said to be riding the gravy train. Another common use of the term is to describe a person’s ability to make a lot of money with a minimal investment of time, effort, or resources. Acting, singing, or otherwise performing, playing professional sports, creating an invention and collecting royalties, or making lucrative investments are often considered such activities.
The term riding the gravy train probably originated from phrases such as "everything else is gravy," which people sometimes use to describe a great deal of profit after expenses. Gravy is a rich, decadent, and fattening food, and the word is frequently used to describe luxuries or large amounts of money. A train ride is easy and relaxing, taking a person where he wants to go without any effort on his part.
Many times, a turn of phrase is derived from common words that can be expanded depending on how they are used or who is saying them, and gravy train is no exception. It's also the name of a national brand dry dog food. When one mixes in water, the coating on the kibbles makes gravy. The term is also used in various song lyrics, as any Pink Floyd fan knows.