one's head off

Adverb

Without restraint, hesitation, or inhibition; endlessly.

Japanese Meaning

遠慮やためらい、抑制なしで、無限に続く様子 / 躊躇なく、抑え込まずに行動する様子 / 制限なく、断固として行われる様子

When one drinks too much, one might sing one's head off, without restraint or inhibition.

お酒を飲みすぎると、遠慮やためらいもなく思い切り歌ってしまうことがある。

Sense（1）

Without restraint, hesitation, or inhibition; endlessly.

He has been worrying his head off all morning about how he will do on the finals.

more one's head off

（ comparative ）

most one's head off

（ superlative ）