1. weep uncontrollably, often for an extended period of time
I was so upset, I cried my eyes out
This informal expression is an exaggeration for effect. By making the hyperbolic claim that you are/have been crying to the point of physical harm, you are emphasizing just how upset you are/were about something. In that context, it is similar to the phrase 'in floods of tears.' It can also be used as an insult, in similar way to 'cry me a river,' if you feel somebody is behaving in an overly emotional or sensitive manner. In this, antagonistic, context, you may occasionally hear this expression being used in a high-pressure professional environment.