Cry Me a River: What does it mean?

You start to complain about something. What do you understand if someone says to you, the phrase, "cry me a river"? See what it means: it said sarcastically to someone whose whining, complaints, or tears fall on unsympathetic ears.

Let me make it clear. When someone says "oh cry me a river" it means they are not sympathetic to your sadness. It's a sarcastic way of saying get over it, like the larger phrase, "Cry me a river, build me a bridge, and get over it!".

In short, the expression 'cry me a river' is an exaggeration used to convey a sense of sarcasm when you don't feel sympathetic to someone's attitudes or something like that.