your head off

(one's) head off

Very intensely or loudly; with no restraint, hesitation, or inhibition. (Used after verbs associated with speech sounds, such as "yell," talk," "laugh," etc.) I'm telling you, Mark's boyfriend is hilarious! He had me laughing my head off when I met him. Suzy started yelling her head off when I told her she couldn't have an ice cream cone. A: "So, has Noah started saying any words yet?" B: "And then some—he's been talking his head off for months now!"
See also: head, off

— your head off

laugh, talk, shout, etc. with a complete lack of restraint or without stopping.
1990 Paul Auster The Music of Chance Now that the kid was out of danger, he began to show his true colors, and it wasn't long before he was talking his head off.
See also: head, off
References in classic literature ?
You must excuse me for taking your head off, but I shall have to do it in order to put your brains in their proper place.
Might as well be dead an' done with it as work your head off that way.
He walks the poop darting gloomy glances, as though he wished to poison the sea, and snaps your head off savagely whenever you happen to blunder within earshot.
Taylor's defence solicitor, Andrew Gibb, said: "You were rocking back and fore in the chair and were banging your head off the wall.