Green’s Dictionary of Slang

break a leg! excl.

[theatrical superstition outlaws the actual phr. ‘good luck’; note Ger. Hals-und-Bein bruch (May you break your neck and leg)]

usu. to an actor, good luck!

Bulletin Nat. Theatre Conf. 11-12 31/1: Then the backstage goodluck line to everyone else. "Break a leg, Harry’.
[[US]News (Frederick, MD) 18 June 4/6: Among the many sayings for ‘good luck,’ you can hear actors whisper ‘neck and leg break’ to each other as the footlights dim and the curtain rises each opening night. Although ‘neck and leg break’ sounds more like a call for a wrestling arena, theatrically it means, ‘good luck’].
[US]Gettysburg (PA) Times 29 May 4/8: In the theater, they say ‘break a leg’ to an actor just before he goes on stage, but it really means ‘good luck.’.
Little & Cantor Playmakers 90: Implicit in the relationship of actor and audience are violence and hostility: the cliche phrases associated with this relationship abound in references to destruction, death, and sexual conquest. ‘Merde’ and ‘Break a leg’* are common actor’s telegrams. [...] Note: *Originally, Hals und Beinbruch, from the German.
[US](con. 1945) M. Angelou Gather Together In My Name 132: ‘Okay Rita, break a leg.’ Show-business talk. I grinned.
[US]R. Sabbag Snowblind (1978) 204: They busted him right there in the airport [...] Break a leg, sucker.
[UK]P. Theroux Family Arsenal 257: ‘I’m opening tomorrow in Peter Pan.’ ‘Break a leg,’ said Hood.
[US](con. c.1970) G. Hasford Short Timers (1985) 163: Alice takes the point. I say ‘Break a leg, Jungle Bunny.’.
[US]H. Ellison All the Lies in Shatterday (1982) 155: Break a leg, Jimmy.
[US]R. Price Breaks 328: Break a leg, kiddo . . . break two.
[US]D. Burke Street Talk 2 85: Break a leg!
‘Sniffer’ [Internet] Well, Sue, it looks like the audience is ready for the big gig and some serious ropework. Break a leg, kid, it’s show time.