Meaning
Go ahead freely; alternatively, make an exhausting all-out effort. Current; permissive use can sound sarcastic Regional use: Strongly established in United States slang; earliest located example is Australian.
Origin
The slang phrase refers to working oneself to exhaustion, not to a boxing knockout. Dictionaries mark it as U.S. slang, and American examples become frequent in the 1930s, but a 1924 South Australian example currently predates the located U.S. evidence. The permissive go ahead sense developed from a sometimes sarcastic invitation to expend as much effort as one wished.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- don't knock yourself out
- go ahead and knock yourself out
- knock oneself out
Usage Examples
- If you want to catalogue every button by colour, knock yourself out.
- Nina knocked herself out preparing a dinner that vanished in ten minutes.