Cry Someone A River Meaning

(idiomatic, usually sarcastic, by extension) To try to obtain the sympathy of another person by complaining or sniveling.

Example: 2008, Michele Hanson, "I cry over anything lately,", 4 Mar. (retrieved 20 Oct. 2008):
  It is rather shaming to be quite so wet over nothing in particular, but at least Fielding does it too. He cries gallons over slow-motion bits at the ends of films, especially Gladiator, and begins to worship Roman values, then Italian footballers kissing in slo-mo to the strains of Nessun Dorma. Sniffle, sniffle. And QPR being relegated in 1996. He can cry you a river over that one, and over a darling little clump of daffodils growing by the traffic island.
1968, A. B. Geraci, "Letter to Editor: PAT Should End Its Free Passes," Pittsburgh Post-Gazette, 3 Oct., p. 16, (retrieved 20 Oct. 2008):
  Port Authority Transit should cry me a river. Before raising fares it should cut an unnecessary expense.