cry heart out(redirected from sing heart out)
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 outand sing one's heart out; play one's heart out; sob one's heart out
Fig. 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.