cry (one's) heart out
To cry for an extended period of time. Poor Jane really cried her heart out during the funeral service. I can't watch those sappy movies because I just cry my heart out every time.
cry one's heart out
and sing one's heart out; play one's heart out; sob one's heart outFig. to do something with vigor or intensity. She suffered such grief—alone and sobbing her heart out. The bird sang its little heart out each morning.
cry your heart out
or sob your heart out
INFORMALCOMMON If you cry your heart out or sob your heart out, you cry a lot. Note: The heart is traditionally regarded as the centre of the emotions. I threw myself on to the bed and cried my heart out. I had never known her cry, and here she was sobbing her heart out. Compare with your heart out.