cry (one's) eyes out
To cry for an extended period of time. Poor Jane really cried her eyes out during the funeral service. I can't watch those sappy movies because I just cry my eyes out every time.
cry one's eyes out
Fig. to cry very hard. When we heard the news, we cried our eyes out with joy. She cried her eyes out after his death.
cry one's eyes out
Also, cry one's heart out. Weep inconsolably. For example, Wendy was so homesick that she was crying her eyes out, or At funerals Ruth always cries her heart out. [c. 1700]
cry your ˈeyes out
cry a lot and for a long time: My son cried his eyes out when we told him we couldn’t afford a new bike. OPPOSITE: laugh your head off