be shouting your head off
be shouting (one's) head off
To be yelling a lot or excessively. The victim was shouting her head off—that's how we were able to find her in the burning building.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
be shouting your head offINFORMAL
If you are shouting your head off, you are shouting a lot. There was one bloke in the box shouting his head off. Note: You can use other verbs with similar meanings to shout in this way. They were yelling their heads off.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012