Gravy Train Meaning

(idiomatic, politics) A gorging on luxuries, since someone else foots the bill.

Example: 1895. Courier of Connellsville, November 1895 (as quoted by Michael Quinion):
  Johnston claims that Reuben Nelson and another tall negro were in New Haven the night of the escape and that they broke into the lockup. Johnson further states that the next day Nelson laughingly told him that the New Haven lockup was 'a gravy train'. "
1970 December 1970, Alex Poinsett, “Is There a Plot to Kill Mayor Hatcher?”[1], Ebony, volume 26, number 2, Johnson Publishing, ISSN 0012-9011, page 146:
  Hatcher derailed the gravy train by consolidating City Hall operations into five general departments headed by three special assistants and two members of the Board of Works.
1975. Pink Floyd. Have a Cigar (song):
  And did we tell you the name of the game, boy, we call it riding the gravy train.
2008, Christopher C. Horner, “Heretics, Speak Out”, in Red Hot Lies: How Global Warming Alarmists Use Threads, Fraud and Deception to Keep You Misinformed[2], Regnery Publishing, ISBN 9781596985384, Conclusion, page 340:
  It is clear that dissent can no longer be tolerated, and no one is above using their position—be it academic, governmental, political or otherwise—to stifle thought that frightens them or threatens to upset the gravy train.