cry heart out(redirected from sing heart out)
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.
cry/sob your heart out(informal)
to cry a lot Poor little love, her cat died and she's been crying her heart out all afternoon.